After Democratic Senate candidates gained two seats Nov. 6, despite pundits' speculation just one year earlier that the party would lose its majority, and independent Sen.-elect Angus King (Maine)'s decision to caucus with Senate Democrats, the party now has a total of 55 seats compared with Republicans’ 45 in the 113th Congress.

But with the right candidates and a favorable national political environment, the GOP will have opportunities to close that gap and possibly win the six seats necessary to take back the chamber in 2014.

Twenty Democratic senators are up for reelection in 2014, compared to only 13 Republicans. Despite the Democratic successes the last time this group of senators was up for election in 2008, many of their seats are in Republican-leaning, or swing, states.

An initial analysis of the 2014 Senate races -- primarily based on the partisan leanings of each state and the perceived strength of the incumbents -- shows 12 Democratic seats that are potentially in play, compared with just two Republican seats that could be vulnerable, ensuring that Democrats will almost exclusively be playing defense in 2014.

Here is a rundown of these 14 races, in alphabetical order by state, with party designation indicating the party of the senator up for reelection in 2014:

Alaska (D): In 2008, former Anchorage Mayor Mark Begich (D) narrowly defeated incumbent Sen. Ted Stevens (R), a mainstay of Alaska politics who was under indictment. Since then, Begich has been gearing up for a tough reelection battle in this red state, where many Republicans already are lining up to take him on. Lt. Gov. Mead Treadwell (R), and Joe Miller (R), who unsuccessfully ran for Senate in 2010, suggested they may run against Begich. Other potential candidates include Gov. Sean Parnell (R), current Anchorage Mayor Dan Sullivan (R) and former Lt. Gov. Loren Leman (R).

Arkansas (D): Sen. Mark Pryor (D), first elected in 2002, is among the last of his kind: a popular Southern Democrat in a deeply red state -- he even ran unopposed in 2008. However, after former Sen. Blanche Lincoln (D) was handily defeated in 2010, state and national Republicans are bullish on taking Pryor down, and he should face a top-tier challenger. Reps. Tim Griffin (R) and Steve Womack (R), as well as Rep.-elect Tom Cotton (R) -– seen as a rising star in the party -– have not ruled out challenging Pryor.

Colorado (D): Sen. Mark Udall (D) was easily elected to an open seat in the 2008 Democratic wave, defeating his opponent by more than 10 percentage points. Though 2014 may be more favorable to the GOP, the party likely will need a top-tier candidate to defeat Udall. Former Lt. Gov. Jane Norton (R), who lost in the 2010 Republican Senate primary to a Tea Party-backed candidate, is being floated as a possible candidate. Other potential candidates include Reps. Cory Gardner (R), Doug Lamborn (R) and Mike Coffman (R), former Gov. Bill Owens (R), state Attorney Gen. John Suthers (R), and Ken Buck (R), who defeated Norton in the 2010 Republican primary, but went on to lose the general election.

Iowa (D): Sen. Tom Harkin (D), who will be 74 in 2014, has not yet indicated whether he will be seeking a sixth term, but either way his seat likely will be targeted by Republicans. Tea Party favorite Rep. Steve King (R) has not ruled out running in two years, and Lt. Gov. Kim Reynolds (R) and Rep. Tom Latham (R) also are being floated as potential candidates.

Kentucky (R): Senate Minority Leader Mitch McConnell (R) narrowly escaped defeat in 2008, and will run for a sixth term in 2014. McConnell has been preparing for this race for a few years now and already has amassed a $7 million war chest. In September, he hired the former chief strategist of Rep. Ron Paul's (R-Texas) presidential campaign to lead his reelection effort. Democrats have a deep bench in this red state; Secretary of State Alison Lundergan Grimes (D), Lt. Gov. Jerry Abramson (D) and even actress Ashley Judd have expressed interest in challenging McConnell.

Louisiana (D): Moderate Sen. Mary Landrieu (D) was considered the most vulnerable incumbent up for reelection in 2008, when she narrowly won a third term. Landrieu, who is the only remaining statewide-elected Democrat in this deeply red state, will surely be a top target for Republicans in 2014. Rep. Bill Cassidy (R) has publicly expressed interest in challenging her.

Maine (R): With Republican Sens. Olympia Snowe and Scott Brown exiting the Senate this January, Sen. Susan Collins (R) may be the last truly moderate Republican left in the upper chamber. It is unclear whether Collins, who is very popular in the state, will seek a fourth term. If she runs and escapes the inevitable primary challenge on her right flank, she will be heavily favored to win another term. If she decides to retire or is defeated in the primary, this could become one of the few Democratic pick-up opportunities of 2014.

Massachusetts (D): Sen. John Kerry’s (D) name is reportedly on President Barack Obama’s short lists for secretary of state and secretary of defense. If he joins the cabinet, it would give outgoing senator Brown (R), who is still popular in the state, a chance to make a quick comeback bid. However, Democrats have a deep bench to choose from in the state and Senate Majority Leader Harry Reid is still quite confident that the seat would stay in Democratic hands in the event of a special election.

Minnesota (D): Former liberal talk show host and comedian Al Franken (D) defeated incumbent Sen. Norm Coleman (R) by 312 votes in 2008 after a seemingly endless recount. Republicans will surely make ousting Franken a top priority in 2014. Besides Coleman, potential challengers include Reps. Erik Paulsen (R) and Michele Bachmann (R). Former Gov. Tim Pawlenty (R), who ran an unsuccessful presidential bid in 2012, is unlikely to run since he decided to become a banking lobbyist earlier this year.

Montana (D): Sen. Max Baucus (D), who saw his approval ratings drop after playing a prominent role in the passage of the Affordable Care Act, might be vulnerable to a primary challenge from popular outgoing Gov. Brian Schweitzer (D). Rep.-elect Steve Daines (R) and outgoing Rep. Denny Rehberg (R), who lost his 2012 Senate bid, are potential Republican contenders.

New Hampshire (D): Sen. Jeanne Shaheen (D) defeated incumbent Sen. John E. Sununu (R) 52 percent to 45 percent in 2008. Despite her lackluster fundraising, her strong approval numbers suggest that it will be difficult to unseat her. Sununu may be eyeing a comeback bid, but the GOP has several alternate candidates, including two congressmen who were ousted this year, Reps. Frank Guinta and Charlie Bass.

North Carolina (D): State House Speaker Thom Tillis (R) is seen as the top recruit to take on freshman Sen. Kay Hagan (D), who is considered one of the most vulnerable incumbents of the cycle, given her mediocre approval ratings and the Republican lean of the Tar Heel State.

South Dakota (D): Former two-term Gov. Mike Rounds (R) announced Thursday that he will challenge incumbent Sen. Tim Johnson (D), who has not indicated if he is running for a fourth term. But with Rounds as the likely nominee, this seat is one of the best Republican pick-up opportunities in the country.

West Virginia (D): After winning reelection comfortably in this red state in 2008, Sen. Jay Rockefeller's (D) future remains uncertain. He will be 77 in 2014, and has not indicated whether he will run for another term. Even if he does, he may face a strong opponent in Rep. Shelley Moore Capito (R), who announced her bid earlier this week. However, her candidacy already has gotten some backlash from conservative groups, so she may not have the primary field to herself.

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  • Alabama

    Sen. Jeff Sessions (R) will be up for reelection in the Yellowhammer State, although the incumbent should be a safe bet in one of the reddest areas of the country. Republican presidential nominee Mitt Romney won Alabama by more than 20 points, and Sessions is three-for-three in his Senate bids.

  • Alaska

    Surprising to some, the home state of Sarah Palin elected a Democratic candidate to the U.S. Senate in 2008, when Sen. Mark Begich (D) narrowly defeated embattled former Sen. Ted Stevens (R). Before then, Alaska had not elected a Democrat since 1974. In 2014, it appears the contest will again be headed for the competitive column. Begich will have to do all he can to retain his seat in this Republican-leaning state.

  • Arkansas

    With an <a href="http://www.uark.edu/depts/plscinfo/partners/arkpoll/12/2012_Arkansas_Poll_Summary_Report.pdf" target="_hplink">approval rating over 50 percent</a>, Sen. Mark Pryor (D) should feel safe in an attempt to win his third election for the seat. This deep red state is willing to elect likeable Democratic candidates -- Mike Beebe (D) is the current sitting governor, and the Clintons hail from Arkansas. Nevertheless, Pryor may be facing a formidable opponent in two years. With every election, voters there favor Republicans more and more.

  • Colorado

    The senior senator from Colorado, Mark Udall (D), has already announced his intention to run again. This swing state should feature a competitive race, as Udall has middling approval numbers, and the GOP has a host of candidates from which to choose. The Democrat understands it will be a tough fight, saying last year that his 2014 reelection is akin to <a href="http://www.rollcall.com/issues/57_39/mark_udall_conquered_many_mountains_before_capitol_hill-209329-1.html?pos=oathh" target="_hplink">climbing Mount Everest</a>. Udall does have one bright spot so far: In a hypothetical matchup against a general Republican opponent, he leads 45 percent to 38 percent, <a href="http://www.publicpolicypolling.com/main/2012/11/obama-leads-by-6-points-in-colorado-4-in-nevada.html#more" target="_hplink">according to Democratic-leaning Public Policy Polling</a>.

  • Delaware

    Sen. Chris Coons (D) won a 2010 special election for Vice President Joe Biden's old seat and is the early favorite in 2014. It will mark 20 years since Delaware elected a Republican to the U.S. Senate, and President Barack Obama (D) handily carried the state in 2012. Lo and behold, controversial Christine O'Donnell could face Coons again. In September, she stated that she was considering another run, <a href="http://www.huffingtonpost.com/2012/09/16/christine-odonnell-2014-senate_n_1888022.html" target="_hplink">saying</a>, "I think I owe that to my supporters." And support surrounding Joe Biden's son, Beau Biden, may begin mounting for a primary challenge if Democrats don't like their prospect. Either way, Delaware may acquire another national spotlight in 2014.

  • Georgia

    Saxby Chambliss (R), the junior senator from Georgia, will defend his incumbency in 2014. In what is often considered a safe red seat, this might be a surprise race to watch in two years. Chambliss had to face his 2008 Democratic opponent in a runoff election to determine the winner, and President Barack Obama only lost the state in 2012 by eight points, a differential that a favorable Democratic candidate could overcome. Chambliss, whose <a href="http://www.publicpolicypolling.com/pdf/PPP_Release_GA_0406930.pdf" target="_hplink">last approval rating</a> came in at 38 percent while 33 percent disapproved, is probably safe, but first he might have to make it out of a primary fight. Those on the right have indicated they may challenge him, especially since his recent comments that he's willing to break from Grover Norquist's no-tax pledge.

  • Idaho

    Consider this one safe: A Republican incumbent in a Republican-heavy state, Sen. Jim Risch (R) should breeze to reelection in 2014.

  • Illinois

    If Sen. Dick Durbin (D) confirms his intent to run for reelection, he will be a heavy favorite in Illinois. Durbin, the Senate majority whip, has been serving since 1997 and has won his three previous races by at least 15 percent, a margin that would be hard for even the strongest GOP candidate to overcome. Nonetheless, recently defeated Rep. Joe Walsh (R) <a href="http://www.dailyherald.com/article/20121107/news/711079754" target="_hplink">may jump into the race</a>, which would certainly draw national attention because of his Tea Party support.

  • Iowa

    In what would mark 30 years since running his first election for the U.S. Senate, Tom Harkin (D) may face a well-known Republican candidate in 2014. Rumors are swirling about who will take on the veteran, from current Gov. Terry Branstad (R) to Tea Party ally and Rep. Steve King (R). Regardless, Harkin is probably the slight favorite at this point, leading a generic Republican opponent 48 percent to 40 percent in <a href="http://www.publicpolicypolling.com/main/2012/11/obama-leads-by-2-points-in-iowa-and-new-hampshire.html#more" target="_hplink">PPP's latest survey</a>.

  • Kansas

    With a positive net <a href="http://www.surveyusa.com/client/PollReport.aspx?g=0817cb1b-e6e3-4c23-b86a-9104d4230d45" target="_hplink">approval rating</a>, Sen. Pat Roberts (R) should not be worried about 2014. If he runs, his Democratic opponent will be fighting an uphill battle, challenging a three-time incumbent in the Senate and a member of Congress since 1981.

  • Kentucky

    Make a note of this one: Senate Minority Leader Mitch McConnell (R) will be up for reelection in 2014. Not only could he face a primary challenge, the Democrats are expected to bring their best in the general election. The <a href="http://www.huffingtonpost.com/2012/11/09/ashley-judd-floated-as-kentucky-senate-candidate-would-cahllene-mitch-micconnell_n_2101162.html" target="_hplink">prospects include</a> actress Ashley Judd, which would immediately make this a nationally viewed race. McConnell will want to keep his approval ratings where they are if he's going to win. 51 percent of Kentucky voters currently <a href="http://www.courier-journal.com/article/20120916/NEWS0106/309170030/Mitch-McConnell-Rand-Paul-rated-favorably-Bluegrass-Poll-shows" target="_hplink">approve</a> of the job he's doing.

  • Louisiana

    Sen. Mary Landrieu, the Democrat representing Louisiana, will be up for her fourth election. Landrieu is considered a very moderate Democrat, which she will need to emphasize in red Louisiana. She won her last election by 6 percentage points, and will be in a tight contest in 2014. She has yet to win a Senate race by more than 6 points.

  • Maine

    It's unclear whether Sen. Susan Collins (R) will try to defend her incumbency in 2014, but with sky-high approval ratings and a moderate tone, she would put up a strong fight in Maine. Voters there just elected an independent in Sen.-elect Angus King, and Collins can sell herself as a centrist. In the <a href="http://www.publicpolicypolling.com/pdf/2011/PPP_Release_ME_1102.pdf" target="_hplink">latest PPP poll</a> of the state, the senator garnered 62 percent of the vote against a generic Democratic opponent, a welcome sign to her if she decides to run.

  • Massachusetts

    Will he or won't he? Be in the Obama administration, that is. Longtime senator and former presidential nominee John Kerry (D) was thought to be a favorite to replace Hillary Clinton as secretary of state, but now speculation has started surrounding the possibility of Kerry as the next defense secretary. He's the favorite in blue Massachusetts in 2014, but it is all dependent on what happens in the near future. Watch out for recently defeated Sen. Scott Brown (R) to make another appearance, particularly in a special election for Kerry's seat.

  • Michigan

    Serving since 1979, six-time incumbent Sen. Carl Levin (D) <a href="http://www.politico.com/news/stories/1112/83680.html" target="_hplink">expects</a> to make a decision on his reelection status early next year. This is a safe Democratic seat if Levin runs. Otherwise it could be competitive. Gov. Rick Snyder (R) showed in 2010 that a Republican can win a statewide race. Wait and see on this one.

  • Minnesota

    Sen. Al Franken (D) has already launched his 2014 campaign website, leaving no doubt he will seek reelection in what might turn out to be another close contest. In 2008, he defeated former Sen. Norm Coleman (R) by just 312 votes after a contentious recount. Bachmann, Pawlenty and yes, Coleman, have all had their names floated as potential challengers. Franken leads all three in hypothetical matchups and has <a href="http://www.publicpolicypolling.com/pdf/2011/PPP_Release_MN_1008.pdf" target="_hplink">decent approval ratings</a>. The Independence Party of Minnesota may also put up a fight after gaining 15 percent of the vote in 2008. This contest leans towards Franken, but will surely be competitive.

  • Mississippi

    Sen. Thad Cochran (R) is the heavy favorite in 2014 if he doesn't retire. Voters in Mississippi haven't elected a Democrat to the U.S. Senate in over 30 years.

  • Montana

    Facing tough approval numbers, Sen. Max Baucus (D) may have a primary battle on his hands for 2014. Current Gov. Brian Schweitzer (D) could try to oust Baucus, although Schweitzer might be looking to 2016 and the presidency instead. If Baucus makes it out of a primary, expect a close contest in Montana similar to the senate race in 2012. And Baucus will be ready -- he <a href="http://missoulian.com/news/state-and-regional/baucus-readying-for-senate-re-election-campaign-in/article_a131f560-7c68-11e1-9a7e-001a4bcf887a.html" target="_hplink">has over $3 million</a> for his campaign and has already run an ad.

  • Nebraska

    Former Nebraska governor and current Sen. Mike Johanns (R) should win his seat in 2014, barring a dramatic shift in Nebraska's sentiment towards the incumbent.

  • New Hampshire

    Democratic Sen. Jeanne Shaheen defeated former Sen. John E. Sununu (R) in 2008, but could face him again in 2014. That would mark three races between the two, with Sununu having won the first contest for the U.S. Senate in 2002. Shaheen has little money at the moment and won her last election by 6.5 points. In the swing state of New Hampshire, this might be another close election in two years.

  • New Jersey

    Sen. Frank Lautenberg (D) has not indicated whether he will seek reelection, and if he does, he may face a primary battle from Democrats. <a href="http://www.philly.com/philly/gallery/NJ_Poll_Menendez_Kyrillos_US_Senate_race_2012.html?viewGallery=y" target="_hplink">In September</a>, 34 percent of New Jersey voters had a favorable impression of the senator, while 29 percent viewed him unfavorably. If Lautenberg retires, might we see a Cory Booker entrance into the contest? Keep an eye on New Jersey -- it could be a fun race to watch.

  • New Mexico

    Tom Udall (D), the junior U.S. senator from New Mexico, won his previous election by more than 20 points. Voters generally approve of the job he's doing, and New Mexico just elected another Democrat to the Senate.

  • North Carolina

    Over $200,000 has already been raised for Sen. Kay Hagan (D) on ActBlue, a Democratic fundraising site. And she will need all the help she can get, as she is considered to be in a tight race in 2014 with mediocre approval ratings in a lean-Republican state.

  • Oklahoma

    In Oklahoma, Sen. Jim Inhofe (R) would most likely retain his seat if he runs in 2014. He's four-for-four in his Senate elections.

  • Oregon

    Sen. Jeff Merkley (D) joins the ranks of Democrats with middling approval numbers who will be defending a seat in 2014. In a <a href="http://www.publicpolicypolling.com/pdf/2011/PPP_Release_OR_062712.pdf" target="_hplink">June 2012 PPP poll</a>, Merkley trailed Republican Rep. Greg Walden by two points but leads other hypothetical opponents by at least six points. This race might be a surprising one to watch, although Merkley should feel better after a nearly 12-point win by President Barack Obama in early November.

  • Rhode Island

    Rhode Island's entire Washington delegation is Democratic, and Sen. Jack Reed (D) should have an easy time in a 2014 election. He's won his last two contests with over 70 percent of the vote, and his <a href="http://www.wpri.com/dpp/news/politics/local_politics/campaign-2012-poll-results-mon-11" target="_hplink">job approval</a> tops 50 percent.

  • South Carolina

    Only 29 percent of South Carolina voters think Sen. Lindsey Graham (R) is too liberal, but he may face a primary fight from the right in 2014. Even with mediocre approval numbers, Graham should be able to hang on to his job in a general election -- he won his last race with 58 percent of the vote.

  • South Dakota

    South Dakota could provide an exciting election come 2014. If he runs, current Sen. Tim Johnson's (D) most likely opponent at this point is former Gov. Mike Rounds (R), who has officially announced his candidacy. Rep. Kristi Noem (R) has also been noted as a possible contender. This seat could flip from left to right, but South Dakota voters are willing to keep it Democratic with a favorable candidate.

  • Tennessee

    Like Sen. Lindsey Graham (R-S.C.), the senior senator from Tennessee Lamar Alexander (R) is expected to face a primary fight <a href="http://blogs.wsj.com/washwire/2012/09/28/tea-party-activists-plan-2014-targets/" target="_hplink">from Tea Party activists</a>. Whichever Republican makes it out of that contest is the safe bet to win the general election. Tennessee hasn't elected a Democratic nominee since 1990, when the state chose Al Gore.

  • Texas

    Texas is expected to stay Republican in 2014 when incumbent Sen. John Cornyn (R) will be up for reelection. He was recently elected the Senate minority whip, placing him behind only Sen. Mitch McConnell in leadership for the Republicans. Cornyn doesn't have the highest approval ratings, but it would come as a surprise if a Democrat took this seat. Sen.-elect Ted Cruz (R) just won the state by 16 points.

  • Virginia

    Sixty percent of Virginia voters <a href="http://www.quinnipiac.edu/institutes-centers/polling-institute/virginia/release-detail?ReleaseID=1813" target="_hplink">approve</a> of the job Sen. Mark Warner (D) is doing in the Senate, and 58 percent view him favorably. He would face a challenging fight in 2014, but even in swing state Virginia, expect Warner to be an elected official for years to come -- he's also been mentioned as a possible 2016 presidential candidate.

  • West Virginia

    West Virginia should provide an intriguing race in 2014. In a poll from last year, Sen. Jay Rockefeller (D) trailed Rep. Shelley Capito (R) by 4 percentage points. A plurality of voters, however, <a href="http://www.publicpolicypolling.com/pdf/2011/PPP_Release_WV_1006.pdf" target="_hplink">approve</a> of the job he's doing, and Rockefeller has name recognition. Even if he doesn't retire, the race should be competitive, as West Virginia is becoming more favorable to the GOP.

  • Wyoming

    Wyoming hasn't elected a Democrat to the U.S. Senate in over forty years. Sen. Mike Enzi's (R) only competitive opposition, then, might come <a href="http://www.huffingtonpost.com/2012/05/08/liz-cheney-senate-mike-enzi-wyoming_n_1500743.html" target="_hplink">from</a> Liz Cheney, the former vice president's daughter. That would mean a primary challenge if Enzi runs, with Cheney drawing national attention to the race.