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.