By Mark Felsenthal

URBANDALE, Iowa, Sept 1 (Reuters) - President Barack Obama tried to bolster his re-election campaign on Saturday with a fierce critique of the Republicans' convention and a plea to supporters to cast their ballots as early as possible.

Speaking to a crowd of 10,000 in the battleground state of Iowa, Obama said rival Mitt Romney and his fellow Republicans had offered no new ideas when they held the national spotlight for three days during their convention in Tampa.

"What they offered over those three days was more often than not an agenda that was better-suited for the last century," Obama said. "We might as well have watched it on a black-and-white TV."

Obama criticized Romney for failing to mention the war in Afghanistan or his plans for veterans care in his speech, and said he had failed to outline a credible plan to boost the economy.

"There was a lot of talk about hard truths and bold choices ... but no one ever actually bothered to tell you what they were," Obama said.

Obama is gearing up for his own star turn next Thursday at the Democratic convention in Charlotte, North Carolina, where he will lay out his argument for re-election in a football stadium that can hold almost 75,000 people.

The speech is likely to offer few surprises: Obama has been arguing since June that the election is a choice between continuing the policies he enacted in his first term, such as keeping his health reforms in place and bolstering education spending, and returning to policies enacted under Republican President George W. Bush that hollowed out the middle class in order to cut taxes for the wealthy.

Romney appears to have gained little ground after his high-profile speech at the end of the national convention. Though his speech was seen by 30 million television viewers, much of the chatter afterward was devoted to the antics of Hollywood icon Clint Eastwood, who preceded Romney with a rambling, at times incoherent critique of Obama.

The modest bump in popularity that Romney enjoyed during the week appears have dissipated, according to a rolling Reuters/Ipsos poll, and Obama now leads 44 percent to 43 percent. The convention did improve Romney's image in the eyes of voters, but he still lags in several measures of favorability.

Obama, likewise, could see a minimal boost from his own convention speech. The overall dynamic of the race has changed little in recent months, and both sides say they expect the election to be close.


TIME FOR A NEW COACH?

Romney has sought to make the election a referendum on Obama's economic performance. He told a crowd of 3,000 in Cincinnati that Obama had failed to deliver on a promise to create jobs - a central theme of his economy-focused campaign.

"If you have a coach that's zero and 23 million, you say it's time to get a new coach," Romney told a rally in Cincinnati, referring to the number of Americans who his campaign are unemployed or underemployed. "It's time for America to see a winning season again, and we're going to bring it to them."

The convention did give Romney one tangible benefit: He is now free to unleash millions of dollars worth of television advertising that he had been prohibited from using until he officially captured his party's nomination.

The Obama campaign expects that they will be outspent by Romney and his allies on TV. They hope to neutralize that advantage with a strong get-out-the vote effort which has been more than a year in the making.

Early voting is a crucial part of that strategy.

Though the Nov. 6 election is months away, voters begin casting ballots in a matter of weeks. Iowa opens its voting process on Sept. 27, while Virginia, another crucial battleground state, begins voting on Sept. 22.

Obama urged supporters in Iowa to cast their votes as soon as possible. The campaign hopes to focus more effort on persuading undecided voters if it can "bank" the votes of reliable supporters ahead of Election Day.

"You can be among the very first to vote in this election," Obama told a crowd of about 10,000.

Early voting was a big part of Obama's success in 2008. Nearly one quarter of the 133 million people who voted that year had already cast their ballots by the time election day rolled around, and polls show that Democratic voters in several swing states were far more likely than Republicans to vote ahead of time.

"Locking up those early voters, especially in a key swing state, can make the difference in the outcome of the election," said Brandon Lenoir, a political science professor at Dickinson College in Carlisle, Pennsylvania.

Obama's Democrats are fighting Republican efforts to roll back early voting in several states. They scored a victory in Ohio on Friday when a judge struck down a Republican attempt to close early-voting stations the weekend before the election.

Related on HuffPost:

Loading Slideshow...
  • Situation Room

    May 1, 2011: President Barack Obama and Vice President Joe Biden, along with members of the national security team, receive an update on the mission against Osama bin Laden in the Situation Room of the White House, May 1, 2011. Seated, from left, are: Brigadier General Marshall B. "Brad" Webb, Assistant Commanding General, Joint Special Operations Command; Deputy National Security Advisor Denis McDonough; Secretary of State Hillary Rodham Clinton; and Secretary of Defense Robert Gates. Standing, from left, are: Admiral Mike Mullen, Chairman of the Joint Chiefs of Staff; National Security Advisor Tom Donilon; Chief of Staff Bill Daley; Tony Blinken, National Security Advisor to the Vice President; Audrey Tomason Director for Counterterrorism; John Brennan, Assistant to the President for Homeland Security and Counterterrorism; and Director of National Intelligence James Clapper. Please note: a classified document seen in this photograph has been obscured. (Official White House Photo by Pete Souza)

  • Head Pat

    May 8, 2009: President Barack Obama bends over so the son of a White House staff member can pat his head during a family visit to the Oval Office May 8, 2009. The youngster wanted to see if the President's haircut felt like his own. (Official White House Photo by Pete Souza)

  • Fist-Bump

    Dec. 3, 2009: President Barack Obama fist-bumps custodian Lawrence Lipscomb in the Eisenhower Executive Office Building following the opening session of the White House Forum on Jobs and Economic Growth, Dec. 3, 2009. (Official White House Photo by Pete Souza)

  • Mohawk Baby

    July 4, 2012: President Barack Obama holds a baby while greeting guests during an Independence Day celebration on the South Lawn of the White House, July 4, 2012. (Official White House Photo by Pete Souza)

  • The President

    July 26, 2012: President Barack Obama holds a Cabinet meeting in the Cabinet Room of the White House, July 26, 2012. (Official White House Photo by Pete Souza)

  • Oval Office Chase

    July 9, 2012: President Barack Obama runs around his desk in the Oval Office with Sarah Froman, daughter of Nancy Goodman and Mike Froman, Deputy National Security Advisor for International Economics, July 9, 2012. (Official White House Photo by Pete Souza)

  • First Couple

    June 13, 2012: President Barack Obama and First Lady Michelle Obama wave goodbye to President Shimon Peres of Israel on the North Portico of the White House following the Presidential Medal of Freedom ceremony and dinner in his honor, June 13, 2012. (Official White House Photo by Pete Souza)

  • Holocaust Museum

    April 23, 2012: President Barack Obama tours the United States Holocaust Memorial Museum in Washington, D.C., with Elie Wiesel, Nobel Peace Prize laureate and Holocaust survivor, and Sara Bloomfield, museum director, April 23, 2012. (Official White House Photo by Pete Souza)

  • Golden Girl

    June 11, 2012: President Barack Obama talks with Betty White in the Oval Office, June 11, 2012. (Official White House Photo by Pete Souza)

  • Venus In Transit

    April 24, 2012: President Barack Obama stops to view the moon and Venus before boarding Marine One in Boulder, Colo., April 24, 2012. (Official White House Photo by Pete Souza)

  • 'Sweet Home Chicago'

    Feb. 21, 2012: President Obama joins in singing "Sweet Home Chicago" during the "In Performance at the White House: Red, White and Blues" concert in the East Room of the White House, Feb. 21, 2012. Participants include, from left: Troy "Trombone Shorty" Andrews, Jeff Beck, Derek Trucks, B.B. King, and Gary Clark, Jr. (Official White House Photo by Pete Souza)

  • The Redeemer

    March 20, 2011: "The Obama family was scheduled to tour the Christ the Redeemer statue in Rio before dinner one night. But when heavy fog rolled in, they canceled the visit. After dinner, the fog had dissipated somewhat so they decided to make the drive up the mountain. It was quite clear when they arrived and then the fog started to roll back in. I managed to capture this silhouette as they viewed the statute one last time just before departure." (Official White House Photo by Pete Souza)

  • Water Fight

    June 11, 2011: "The top photograph shows the President having a water gun fight with his daughter Sasha on her birthday weekend at Camp David. Unbeknownst to me, David Lienemann captured a similar photo of the Vice President on the very same day." (Official White House Photos by Pete Souza and David Lienemann)

  • Christmas Card

    Dec. 11, 2011: President Barack Obama, First Lady Michelle Obama, and their daughters, Malia, left, and Sasha, right, sit for a family portrait in the Oval Office, Dec. 11, 2011. (Official White House Photo by Pete Souza)

  • MLK Memorial

    Oct. 14, 2011: President Barack Obama tours the Martin Luther King, Jr. National Memorial in Washington, D.C., Oct. 14, 2011. (Official White House Photo by Pete Souza)

  • Balloon Man

    Oct. 11, 2011: "This photograph by Chuck Kennedy has to catch your eye. It shows Guinness Book of World Records holder John Cassidy performing a balloon act for First Lady Michelle Obama in the Diplomatic Reception Room following a Let's Move event." (Official White House Photo by Chuck Kennedy)

  • Mandela

    June 21, 2011: First Lady Michelle Obama meets with former President Nelson Mandela of South Africa at Mandela's home in Houghton, South Africa, June 21, 2011. (Official White House Photo by Samantha Appleton)

  • Joplin, Mo.

    May 29, 2011: President Barack Obama greets Hugh Hills, 85, in front of his home in Joplin, Mo., May 29, 2011. Hills hid in a closet during the tornado, which destroyed the second floor and half the first floor of his house. (Official White House Photo by Pete Souza)

  • Daycare

    June 9, 2011: President Barack Obama greets children at a day care facility adjacent to daughter Sasha's school in Bethesda, Md., following her 4th grade closing ceremony, June 9, 2011. (Official White House Photo by Pete Souza)

  • Tucson Shooting

    Jan. 10, 2011: President Barack Obama and First Lady Michelle Obama walk towards the White House after observing a moment of silence for the victims of the Arizona shooting, on the South Lawn, Jan. 10, 2011. White House staff joined the President and First Lady for the moment of silence.(Official White House Photo by Chuck Kennedy)

  • What's Up?

    March 7, 2011: President Barack Obama, Prime Minister Julia Gillard of Australia, and members of the Australian and American delegations look up at the presidential seal in the Oval Office ceiling following their bilateral meeting, March 7, 2011. (Official White House Photo by Pete Souza)

  • Inclement Weather

    May 31, 2010: "The skies opened up on Memorial Day outside of Chicago. When the lightning began, the Secret Service told the President that it was too dangerous to proceed. He took the stage by himself and informed the audience that his speech was canceled and that for everyone's safety, they should return to their busses. Later, he boarded a few of the busses to thank them for attending and apologized for not being able to speak." (Official White House Photo by Pete Souza)

  • Power Walk

    July 20, 2010: President Barack Obama and British Prime Minister David Cameron walk across the South Lawn of the White House, July 20, 2010. (Official White House Photo by Pete Souza)

  • Oil Spill

    May 28, 2010: President Barack Obama and Lafourche Parish President Charlotte Randolf, left, inspect a tar ball as they look at the effect the BP oil spill is having on Fourchon Beach in Port Fourchon, La., May 28, 2010. (Official White House Photo by Chuck Kennedy)

  • Finally

    March 21, 2010: President Barack Obama, Vice President Joe Biden, and senior staff, react in the Roosevelt Room of the White House, as the House passes the health care reform bill, March 21, 2010. (Official White House Photo by Pete Souza)

  • First Pitch

    March 31, 2010: President Barack Obama practices his pitching form with personal aide Reggie Love and Jake Levine in the Rose Garden of the White House, March 31, 2010. The President threw out the ceremonial first pitch on opening day of the baseball season prior to the game between the Washington Nationals and the Philadelphia Phillies.

  • 3D

    Feb. 1, 2009: "During a Super Bowl watching party in the White House theatre, the President and First Lady join their guests in watching one of the TV commercials in 3D." (Official White House photo by Pete Souza)

  • Bo

    March 15, 2009: "The Obama family was introduced to a prospective family dog at a secret greet on a Sunday. After spending about an hour with him, the family decided he was the one. Here, the dog ran alongside the President in an East Wing hallway. The dog returned to his trainer while the Obama's embarked on their first international trip. I had to keep these photos secret until a few weeks later, when the dog was brought 'home' to the White House and introduced to the world as Bo." (Official White House photo by Pete Souza)

  • Moment Of Reflection

    Jan. 20, 2009: "President-elect Barack Obama was about to walk out to take the oath of office. Backstage at the U.S. Capitol, he took one last look at his appearance in the mirror." (Official White House photo by Pete Souza)

  • Snowball Fight

    Dec. 19, 2009: "Snowball in hand, the President chases Chief of Staff Rahm Emanuel on the White House colonnade. To escape, Rahm ran through the Rose Garden, which unfortunately for him, was knee-deep in snow." (Official White House photo by Pete Souza)

  • Nobel

    Dec. 10, 2009: President Barack Obama looks at the Nobel Peace Prize medal for the first time at the Norwegian Nobel Institute in Oslo, Norway, Dec. 10, 2009. (Official White House Photo by Pete Souza)

  • Presidential Trio

    Jan. 16, 2010: "President Obama had called on the two former Presidents to help with the situation in Haiti. During their public remarks in the Rose Garden, President Clinton had said about President Bush, 'I've already figured out how I can get him to do some things that he didn't sign on for.' Later, back in the Oval, President Bush is jokingly asking President Clinton what were those things he had in mind." (Official White House photo by Pete Souza)

  • Wounded Warriors

    Oct. 8, 2009: President Barack Obama watches as members of the National Naval Medical Center's Marine Wounded Warrior basketball team play on the White House basketball court, Oct. 8, 2009. (Official White House Photo by Pete Souza)

  • Shoot The J

    Oct. 8, 2009: President Barack Obama takes a shot during a game with Cabinet secretaries and members of Congress on the White House basketball court, Oct. 8, 2009. (Official White House Photo by Pete Souza)

  • Grand Canyon

    Aug. 16, 2009: President Barack Obama looks at the Grand Canyon in Arizona on Aug. 16, 2009. (Official White House photo by Pete Souza)

  • Ted Kennedy

    April 21, 2009: President Barack Obama and Sen. Ted Kennedy walk down the South Lawn sidewalk at the White House April 21, 2009. (Official White House Photo by Pete Souza)

  • The Pope

    July 10, 2009: President Barack Obama and First Lady Michelle Obama meet with Pope Benedict XVI at the Vatican on July 10, 2009. (Official White House photo by Pete Souza)

  • Punch

    July 13, 2009: President Barack Obama feigns a punch while talking about health care reform with Nancy-Ann DeParle, Peter Orszag, Phil Schiliro and Larry Summers in the Outer Oval Office, July 13, 2009. (Official White House Photo by Pete Souza)

  • Teasing

    June 26, 2009: President Barack Obama jokingly reacts to news that staffer Nora Becker will be leaving to pursue a joint MD and PhD in healthcare economics, during the White House staff picnic on the South Lawn, June 26, 2009. (Official White House Photo by Pete Souza)

  • Nancy Reagan

    June 2, 2009: President Barack Obama and former First Lady Nancy Reagan walk side-by-side through Center Hall in the White House, June 2, 2009. To the left of Mrs. Reagan hangs her official White House portrait as First Lady. (Official White House Photo by Pete Souza)

  • Cairo Visit

    June 4, 2009: Secretary of State Hillary Clinton recounts a story to President Barack Obama, Senior Advisors David Axelrod and Valerie Jarrett, outside the Sultan Hassan Mosque in Cairo, Egypt, June 4, 2009. (Official White House Photo by Pete Souza)

  • The Sphinx

    June 4, 2009: President Barack Obama tours the Egypt's Great Sphinx of Giza (left) and the Pyramid of Khafre, June 4, 2009. (Official White House photo by Pete Souza)

  • Behind The Camera

    Feb. 18, 2009: President Barack Obama takes aim with a photographer's camera backstage prior to remarks about providing mortgage payment relief for responsible homeowners at Dobson High School, Mesa, Ariz., Feb. 18, 2009. (Official White House Photo by Pete Souza)

  • First Day

    Jan. 21, 2009: President Barack Obama walks into the Oval Office for his first full day in office, Jan. 21, 2009. His Personal Aide Reggie Love stands nearby. (Official White House photo by Pete Souza)