President Obama and Republican challenger Mitt Romney traded their debate-prep books for stump speeches Tuesday, returning to packed campaign schedules in battleground states for the final two weeks of an increasingly deadlocked campaign.

Romney’s advisers described Obama’s campaign as “desperate” to regain momentum after watching a substantial lead in the polls mostly dwindle away, while Obama’s aides denounced Romney’s performance in the third and final presidential debate and said they remain confident of victory on Nov. 6.

Obama believes he is winning or even in all the swing states, with early voting and turnout among young people and Latinos outpacing the historic levels of 2008, advisers told reporters on a conference call Tuesday. They dismissed rumors that the campaign was pulling out of some battleground states where Romney has recently gained strength.

“The electorate is bigger this year, and our vote margins are, too,” campaign manager Jim Messina said, citing polls and early-vote turnout numbers from Ohio, Iowa, Wisconsin and Florida, among others. As an example, Messina noted that Democratic turnout in Florida at this point four years ago was 250,000 votes behind Republicans, whereas today Democrats are just 38,000 votes behind. Obama won Florida in 2008.

But Romney and running mate Rep. Paul Ryan (Wis.), campaigning in Henderson, Nev., claimed momentum.

Explore the 2012 electoral map and view historical results and demographics

Ryan, his voice unusually scratchy, exhorted the crowd, “We can do better than this. We don’t have to settle for this.”

“Two weeks from today,” he said, Obama“is going to become former President Barack Obama and Mitt Romney is going to be the next president of the United States.”

The new Washington Post-ABC News national tracking poll released Tuesday has 49 percent of likely voters supporting Romney, and 48 percent Obama.

With the last of three contentious debates behind them, each candidate must summon a final burst of energy to make his case to a dwindling number of undecided American voters.

In Nevada, Romney said the debates have “supercharged” his candidacy and charged that Obama has failed to lay out an agenda to spur economic growth.

“His is a status-quo candidacy. His is a message of going ‘forward’ with the same policies of the last four years, and that’s why his campaign is slipping and ours is gaining so much steam,” Romney told a boisterous rally of about 6,000 supporters in Henderson, a Las Vegas suburb.

At his first of two joint rallies with Ryan, Romney said Obama’s campaign is “taking on water” because he was focused more on tearing Romney down than laying out a positive vision for the future of the country.

“You know, he’s been reduced to try to defend characters on ‘Sesame Street’ and word games of various kinds and then misfired attacks after one another,” Romney said. “You know, the truth is that attacks on me are not an agenda…. We can handle two more weeks of the attacks that are coming from Barack Obama, but we cannot handle four more years of what he has given us.”

With the debates behind him, Romney is stepping up his campaigning, planning a series of large rallies in the key battleground states. From Nevada, he and Ryan fly to the Denver area for a joint rally against the sunset at Red Rocks Ampitheater, a famous Colorado concert venue, where they will be joined by New Mexico Gov. Susana Martinez and country singer Rodney Atkins, as well as Kid Rock, the Detroit rocker who sings “Born Free,” Romney’s campaign theme song.

On Wednesday, Romney returns to Nevada for a rally in Reno, a heavily Republican area, and then to Iowa. He also plans to campaign across Ohio, Florida and Virginia later in the week. Advisers said Romney would start delivering his closing argument to voters this week and is considering a major speech on debt and government spending in the coming days.

Obama began his day in Delray Beach, Fla., addressing a raucous crowd of 10,000 supporters. Sounding revved up and not at all like a man in the fight of his political life, he mocked Romney’s shifting positions on several foreign policy issues during the debate Monday night as “a severe outbreak” of “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.’’

Romney’s supporters argued that the debate — in which Obama was more combative, while Romney often expressed approval of the president’s positions — reflected the incumbent’s increasing vulnerability and the challenger’s growing confidence.

Eric Fehrnstrom, a senior adviser to Romney, said that while “Mitt Romney came here to debate America’s position in the world, I think Obama came here to defend his position in the campaign, which has deteriorated.”

Vice President Biden, who has been the Obama camp’s most aggressive attacker throughout this campaign cycle, slammed Romney for reversing himself at the debate and embracing many of Obama’s foreign policy positions.

“They’ve gone from rattling the saber to, you know, being doves carrying, you know, peace — I don’t know what they stand for,” Biden said on “CBS This Morning” the day after the debate. “Look, being president requires a clear vision and a steady hand. That’s exactly what President Obama demonstrated. . . . And it’s exactly what Governor Romney demonstrated was lacking.”

Obama plans to sleep on Air Force One during a cross-country blitz over the next two days that will take him to almost every important battleground state: Ohio, Florida, Virginia, Iowa, Colorado and Nevada. He has scheduled an appearance with Biden in Dayton, Ohio, on Tuesday afternoon and will detour to California on Wednesday for an appearance on NBC’s “The Tonight Show With Jay Leno.”

The Obama campaign is pushing its own closing argument — in the form of a glossy, 20-page pamphlet called “A Plan for Jobs & Middle-Class Security” — that will be mailed, handed out and touted nationwide.

Much of it is a summary of proposals Obama has been offering on the campaign trail for months, such as plans to use half the savings from winding down wars in Iraq and Afghanistan for domestic infrastructure investment; create incentives for companies to bring jobs back to the United States (and end tax breaks for companies that ship jobs overseas); continue investing in “clean” energy; and recruit 100,000 new math and science teachers.

Senior adviser David Axelrod said 3.5 million copies of the blueprint are being mailed to households in swing states, and millions more will be given out door to door. He dismissed Republican critics who blasted the pamphlet as a blueprint of “repackaged ideas,” saying the booklet was meant to grab voters attention and summarize Obama’s goals and plans — not to add new proposals with just two weeks left in the campaign.

“We want to make sure that everybody is focused on the specific things that the president is proposing moving forward,” Axelrod said. “Obviously, a lot of people have made up their minds. There is a small universe of voters who haven’t. We want to make sure those voters have access to the information they need to make the judgment as to which direction they want to go.”

Meanwhile, Restore Our Future, a super PAC supporting Romney’ campaign, is launching a $17.7 million ad buy in key states this week. The buy is for three ads — “Better” and “The New Normal,” which attack Obama’s handling of the economy, and “Genuinely Cares,” a softer spot highlighting Romney’s work with injured veterans. 

Markon reported from Delray Beach, Rucker from Henderson, Nev., and Wilgoren from Washington. Amy Gardner in Washington contributed to this report.