CORAL GABLES, Fla. — For one day of the campaign, at least, President Barack Obama was just the warm-up act.

Hours before Vice President Joe Biden's lone debate with Republican running mate Paul Ryan, Obama appeared loose and at ease in a semi-backup role, his sleeves rolled up at the University of Miami as he railed against rival Mitt Romney before 9,000 screaming college students.

For once, Biden was front-and-center.

Obama's stumble in the first presidential debate against Romney raised the stakes of Biden's performance in Danville, Ky., giving the president's re-election campaign a chance to regain its stride and blunt Romney's recent rise in the polls.

Obama planned to watch the start of the debate aboard Air Force One following an evening fundraiser in Miami, one of his last of the long campaign. Aides said the president called Biden on the way to South Florida to wish him good luck.

The president made no mention of the debate during the rally, choosing instead to criticize his GOP rival and plead with students to vote early beginning on Oct. 27.

"He's trying to go through an extreme makeover," Obama said of Romney. "After running for more than a year in which he called himself `severely conservative,' Mitt Romney is trying to convince you that he was severely kidding."

Taking a mocking tone, the president said Romney was trying to mask his past stances on tax cuts and health care. "Mitt Romney is for whatever you're for. Suddenly, he loves the middle class – can't stop talking enough about them. He loves Medicare, loves teachers. He even loves the most important parts of Obamacare. What happened?"

Obama recited a litany of what he said are the consequences of Romney's policies, taunting that "this new version of Mitt Romney" was running away from the things he promised to do as president. "Tax breaks for outsourcers? Never heard of such a thing. Saying we should cut back on teachers? Doesn't ring a bell."

The crowd roared with delight at the tougher approach. One person in the crowd held aloft an iPad with a simple message for Obama: "Take the gloves off."

At a Miami fundraiser, Obama joked that he wasn't born into "wealth or fame. You hadn't heard of the Obama name before. Let's face it. The first time you heard it you probably thought the guy might be Japanese. Italian. Who knows?" Obama said.

A woman in the audience shouted, "Latino." "Latino! The Obama family from Jalisco," Obama said to laughter.

Obama's campaign said the president planned to travel to Williamsburg, Va., on Saturday for three days of practice before the next debate, when the full glare of the spotlight will return – for good.

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