With the announcement by Iowa Sen. Tom Harkin (D) that he will not seek reelection in 2014, the Senate stands to lose two of the remaining members whose politics were formed during the era of the New Deal coalition.

Harkin and West Virginia Sen. Jay Rockefeller (D), who is also retiring at the end of 2014, are two of the strongest defenders of Social Security, Medicare and Medicaid, and are ardent advocates of an active role for the federal government in the economy.

Harkin first won election to the House in the Watergate wave year of 1974 and won a Senate seat a decade later, in 1984. That same year Rockefeller joined him in the Senate. With the loss of Rockefeller, the Senate will lose perhaps its most outspoken defender of Medicaid.

Harkin was most recently at the forefront of the fight to reform the filibuster, a battle he and other liberals lost. "It's not easy to walk away, but life is fleeting," Harkin told The New York Times in an interview Saturday. "I've had the privilege to be here for 40 years. Too many people hang on to power for too long, and that’s not right."

He told The Des Moines Register he hopes Democrats pick a nominee who is “smart, savvy, knows how to put together a winning campaign and is a good pragmatic progressive.”

The GOP's chance of retaking the Senate increases with the departures of Harkin and Rockefeller, also raising the possibility that Tea Party favorite Rep. Steve King will ascend to the upper chamber.

UPDATE -- 4:58 p.m.: President Barack Obama issued the following statement on Harkin's announcement:

By the time Senator Harkin finishes his fifth term, he will have represented the people of Iowa in the United States Congress for an incredible 40 years. He has served in the U.S. Senate longer than any Democrat in Iowa's history. During his tenure, he has fought passionately to improve quality of life for Americans with disabilities and their families, to reform our education system and ensure that every American has access to affordable health care. Senator Harkin will be missed, and Michelle and I join Iowans in thanking him for his long-standing service and wish him and his wife, Ruth, all the best in the future.

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  • The Numbers

    The House has 233 Republicans and 200 Democrats. Each party should pick up one more seat when two vacancies are filled. Going into the election, the GOP edge was 242-193. Senate Democrats will have a caucus of 55, including two independents, Angus King of Maine and Bernie Sanders of Vermont. Republicans have 45. That's a pickup of two seats for Democrats. <em>(Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>)</em>

  • Women

    The House will have 79 women, including 60 Democrats. At the end of the last session, there were 50 Democratic women and 24 Republican women. The new Senate will have 20 women members, an increase of three. That consists of 16 Democrats and four Republicans. The last Senate had 12 Democratic women and five Republicans. (Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>)

  • Freshmen

    With two vacancies to be filled, the House has 82 freshmen; 47 Democrats and 35 Republicans. As of the end of the last session, 87 of 103 freshmen were Republicans. The Senate will include 14 new faces, with nine Democrats and the independent King. Five are women. New senators include Brian Schatz, who was sworn in on Dec. 27 to fill the seat of the late Hawaii Democrat Daniel Inouye. (Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>) <em>(Pictured at left: Incoming House freshmen of the 113th Congress pose for a group photo on the East steps of the Capitol in Washington, Thursday, Nov. 15, 2012. AP Photo/Susan Walsh)</em>

  • African Americans

    The House will have 40 African-Americans, all Democrats. The number of Democrats is unchanged, although two Republicans will be gone: Allen West, R-Fla., lost his re-election bid, and Tim Scott, R-S.C., was appointed to fill the Senate seat of Jim DeMint, R-S.C., who is retiring. Scott will be the first black lawmaker in the Senate since Roland Burris, who retired in 2010 after filling the Illinois Senate seat of Barack Obama for almost two years. (Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>) <em>(Pictured at left: Rep. Tim Scott, R-S.C., who was appointed by South Carolina Gov. Nikki Haley to replace outgoing Sen. Jim DeMint, R-S.C., walks out of the Republican policy luncheon on Capitol Hill in Washington, Tuesday, Dec. 18, 2012. AP Photo/Susan Walsh)</em>

  • Hispanics

    The new House will have 33 Hispanics, with 25 Democrats and eight Republicans. That's up slightly from last year. The Senate will have three Hispanics: Democrat Robert Menendez of New Jersey, Republican Marco Rubio of Florida and Republican freshman Ted Cruz of Texas. (Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>) <em>(Pictured at left: Rep.-elect Joaquin Castro, D-Texas, speaks with members of the media after a news conference with newly elected Democratic House members on Capitol Hill in Washington, Tuesday, Nov. 13, 2012. AP Photo/Pablo Martinez Monsivais)</em>

  • Other Minorities

    The new House will have nine Asian Americans, all Democrats. There are two American Indians: Tom Cole, R-Okla., and Ben Lujan, D-N.M. (Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>) <em>(Pictured at left: Sen.-elect, current Rep. Mazie Hirono, D-Hawaii, and her husband, Leighton Oshima ride the Senate Subway on Capitol Hill in Washington, Tuesday, Nov. 13, 2012. AP Photo/Harry Hamburg)</em>

  • Other Facts

    According to CQ Roll Call newspaper, the average age of House members in the 113th Congress is 57; the average age of senators is 62. It estimates that the House will include some 277 Protestants and Catholics, 22 Jews, two Muslims and two Buddhists. The Senate will have 80 Protestants and Catholics and 10 Jews. The House will have its first Hindu, Rep.Tulsi Gabbard, D-Hawaii. Senate freshman Mazie Hirono, also of Hawaii, will be the Senate's only Buddhist and its first Asian American woman. Also for the first time, white men will be a minority among House Democrats. (Text <a href="http://www.huffingtonpost.com/huff-wires/20130103/us-new-congress-glance/">via the Associated Press</a>) <em>Pictured at left: Rep.-elect Tulsi Gabbard, D-Hawaii is seen on stage during a news conference with newly elected Democratic House members, on Capitol Hill in Washington, Tuesday, Nov. 13, 2012. AP Photo/Pablo Martinez Monsivais)</em>