On Tuesday, the presidential candidates unveiled their endgames.

After a debate season that reversed the two men’s fortunes in the polls, President Obama indicated that he would run in the last two weeks of the race as an underdog. “I don’t want to lose this election,” he told supporters in an e-mail.

On a day of high-energy rallies, his campaign also announced a grand last-minute gesture. To rebut criticism that Obama has no agenda for a second term, his campaign plans to mail 3.5 million copies of what it calls the “Blueprint for America’s Future,” a repackaging of previously discussed ideas, to swing-state voters.

Republican nominee Mitt Romney, who had been the longtime underdog, signaled that he would finish the campaign as a calm, cautious front-runner. Advisers said he was unlikely to lay out new ideas. From his perspective, why would he?

Obama’s “campaign is slipping,” Romney told a crowd in this Las Vegas suburb, “and ours is gaining so much steam.”

Both men were, in a sense, bluffing — the polls are effectively tied. But each seemed to have settled on the role he would play in the campaign’s last frenetic days; both roles have previously served the candidates well. Romney, who was the front-runner through the GOP primaries, would again be the man destined to victory. Obama, who started in 2008 as a heavy underdog against Hillary Rodham Clinton, would try to reprise that image.

“We’ll know who’s bluffing in two weeks,” David Axelrod, a longtime Obama adviser, said in a conference call with reporters to discuss the state of the race. “I’m looking forward to it.”

A new Washington Post-ABC News tracking poll of likely voters showed Romney leading Obama by one point, 49 percent to 48 percent. The day before, the numbers were reversed, with Obama leading by the same thin margin.

On both days, the meaning was the same: The presidency will probably be decided by a small sliver of voters who may shift in the next two weeks.

Tuesday was the first day of that hyper-compressed campaign, with both candidates seemingly in every swing state at once.

In the morning, Obama was in Delray Beach, Fla., attacking what he said was Romney’s move to more moderate positions. He repeated his latest zinger, that his opponent suffers from “Romnesia.”

“We’re accustomed to seeing politicians change their positions from, like, four years ago,” Obama said. “We’re not accustomed to seeing a politician change their positions from four days ago.”

Behind the scenes, the president’s advisers argued that they hold advantages in the key states needed to win the electoral college vote. They cited figures indicating that early voting and turnout among young people and Latinos — crucial Obama constituencies — are outpacing the historic levels of 2008.

“We [would] win the election if it were held today,” said David Plouffe, a senior White House adviser. “In the battleground states, we think we’ve got many more pathways to 270 electoral votes.”

But Obama’s plaintive e-mail to supporters (“Please don’t wait any longer,” it said) and his massive mail-out of the “Blueprint” were strong signs of worry. In Monday’s debate, Romney renewed a long-standing criticism with the line “Attacking me is not an agenda.” Now, Obama’s campaign said, it would put an agenda in millions of people’s hands, with mailings and door-to-door canvassing. The plan can also be found online at www.barack­obama.com/plans.

It includes familiar Obama ideas such as investing in community colleges, ending tax breaks for companies that outsource jobs overseas and increasing taxes on some people making more than $1 million.

In all-important Ohio on Tuesday, it seemed that Obama’s campaign was still trying to fire up the Democratic base. Vice President Biden appeared at a rally in Toledo, following events Monday in two other Democratic strongholds. Biden and Obama appeared together in Dayton on Tuesday night, drawing a huge crowd.

Romney, by contrast, sounded more confident Tuesday than he has throughout much of his campaign — in which he has often had to correct himself to say “when I’m president,” instead of “if.”

In Henderson, he told the crowd that Obama is “taking on water.”

“He’s been reduced to try to defend characters on ‘Sesame Street’ and word games of various kinds, and then misfired attacks,” Romney said, referring to an Obama ad in which Big Bird makes an appearance.

Romney’s advisers spoke in metaphors of finality.

“The cake is baked,” said Eric Fehrnstrom. “Something structural changed in that first debate, and all the movement has been toward Governor Romney.”

Inside the Romney campaign, advisers think they are getting the election they always wanted — one focused on economic leadership and contrasting visions for the country’s future.

The Republican nominee plans to deliver a major speech this week on the debt and federal spending, and he plans more television ads in which he speaks about his economic plans directly to the camera, advisers said.

As in most presidential campaigns, some of this late-game rhetoric amounts to advisers trying to fake one another out.

On Tuesday, for instance, Obama’s camp said it would remain active in North Carolina, a state that appears to be trending Republican. Romney staffers, in turn, publicly pondered diving back into blue-tinted Pennsylvania and Michigan.

But their main audience is voters, and the campaigns hope to motivate them either through worry or the appeal of joining a winning team.

In Delray Beach, worry already seemed to be working for Obama.

Margot Mueller, 49, showed up at a campaign office on Monday with her 10-year old daughter. She voted for Obama four years ago and is hopeful he will win again. “I still believe in the Democratic philosophy,” she said. “I still feel that too much wealth goes to too few.”

Moments later, an elderly woman named Paula walked into the campaign office. “Would you like somebody to make a few calls?” she asked. “I have a free hour.”

A campaign worker quickly stood up, grabbed a call sheet and hustled Paula into a back room away from a reporter.

“Just call as many people as you can,” the worker said.

Amy Gardner in Washington, Jerry Markon in Nevada, Joel Achenbach in Ohio and Ed O’Keefe in Florida contributed to this report.