COLUMBUS, Ohio – The Republican Party on Sunday launched robocalls to millions of voters in battleground states, playing audio of Hillary Clinton in the primary election portraying her then-opponent Barack Obama as too inexperienced to run against John McCain.

Obama, meanwhile, unveiled a 30-second television ad comparing his own backing from billionaire investor Warren Buffett and retired Gen. Colin Powell to McCain’s weekend endorsement by unpopular Vice President Dick Cheney.

As both campaigns sought to energize voters with two days remaining in the presidential contest, McCain was fighting for comebacks Sunday in Pennsylvania, New Hampshire and Florida, while Obama spent the day in battleground Ohio.

The two campaigns’ moods were markedly different.

McCain and his team were defiant. In Wallingford, outside Philadelphia, the sound system played the theme from “Rocky” as McCain took to the stage in a high school gymnasium to address a crowd of 2,000.

“Let me give you a little straight talk about the state of the race today,” McCain told the crowd. “There’s just two days left, we’re a couple of points behind in Pennsylvania. The pundits have written us off, just like they’ve done before. My friends, the Mac is back.”

McCain also scheduled an evening town hall meeting in New Hampshire, where he’s long had a strong network of support but where he now trails Obama by 10.7 percentage points, according to an average of statewide polls calculated by RealClearPolitics.com. “We wouldn’t go to New Hampshire unless we thought it was winnable,” McCain senior adviser Mark Salter said.

Obama and his surrogates exuded confidence.

“Two days,” Obama told 60,000 supporters in Columbus, where he began the day, before a scheduled evening appearance in Cleveland with singer Bruce Springsteen and a night rally in Cincinnati. While Obama implored supporters to vote, saying, “Don’t think for a minute that power will concede without a fight,” he also said, “This is our time. We’ve got a righteous wind at our backs.”

In Florida, at a rally with Obama’s running mate Joe Biden at Florida State University in Tallahassee, Sen. Bill Nelson said that if turnout is high, “Tuesday night I suspect we’re going to be singing ‘Happy Days Are Here Again.”‘

The robocall by the Republican National Committee and approved by the McCain campaign, plays audio of Clinton minimizing Obama’s experience and the significance of a 2002 speech he gave opposing the invasion of Iraq. Since summer, however, she’s campaigned on behalf of Obama across the country,

“In the White House, there is no time for speeches and on-the-job training,” Clinton said then. “Sen. McCain will bring a lifetime of experience to the campaign, and Sen. Obama will bring a speech that he gave in 2002.”

Clinton spokeswoman Kathleen Strand issued a statement in response to the RNC robocall:

“Senator Hillary Clinton does not approve this message, and as she crisscrosses the country, she has said time and again that the choice in this election could not be more clear. The McCain/Palin ticket offers only more of the same failed policies while the Obama/Biden ticket offers the vision, leadership and positive solutions we need. I wonder why the Republicans aren’t using those words?”

Meanwhile, McCain’s campaign continued going full bore in Pennsylvania. He’s banking on a combination of energizing the GOP base and finding enough Democrats who backed Hillary Clinton but still aren’t sold on Obama. But state polls show Obama ahead by an average of 7 points.

In Columbus, the Obama crowd booed at the mention of Cheney’s name. Obama noted that Cheney said he was “delighted” to endorse McCain, and, alluding to Cheney’s trademark grimace, said, “You’ve never seen Dick Cheney delighted before, but he is” as the crowd laughed. “That’s kind of hard to picture.”

Obama said McCain had earned Cheney’s support with his support for the Iraq war and President Bush’s economic policies.

After revving the audience up with that rhetoric, Obama pledged to seek unity and end partisan divisions.

Biden stressed the same message in Tallahassee. Singling out some vocal McCain supporters at a Democratic rally Sunday, Biden called them “good folks … committed to John’s notions.” He told the crowd at Florida State University that “red and blue” politics must end.

“We have to unite this country,” Biden said. “We can’t move past the politics of division unless we reach out. Somebody’s got to be big enough to stand up and end this. I just want to warn you: We mean it.”

The presidential rivals each had a busy final day of campaigning planned for Monday.

McCain’s schedule was loaded with a seven-stop blitz across the country.

Obama planned a final three-stop swing Monday up the East Coast in GOP states he hopes to convert: Florida, then North Carolina, then a final rally in Northern Virginia. Obama also told reporters traveling with him that he planned to hold a news conference on Wednesday, the day after the election.

Obama will aim to energize black voter turnout, which could be key to the outcome in several states. Recording artists Mary J. Blige, Shawn “JAY-Z” Carter and Sean “Diddy” Combs were to rally for him Monday in Ohio, and Obama’s Florida stop Monday is set for Jacksonville, which has a high percentage of black voters who in recent elections have felt disenfranchised.