Mary Altaffer/AP Photo

LAS VEGAS - President Obama convened the final debate camp of his political career here on Sunday, huddling with top advisers at a posh lakeside resort 20 miles east of the Strip for a three-day crash course on Republican rival Mitt Romney.

Aides said a "debate prep team" had been pouring over hours of old videotape of Romney and other past Republican and Democratic candidates ahead of the meetings to clean strategic insights to pass on to Obama, who was last on a debate stage on Oct. 15, 2008. He has never sparred with Romney in person.

The two men will meet face to face for the first time Wednesday night at the debut 2012 presidential debate in Denver.

Obama is being coached by a group of veteran Democratic operatives and inner-circle White House advisers, aides said, including senior campaign adviser David Axelrod, pollster Joel Benenson, Democratic strategists Anita Dunn and Ron Klain, National Economic Council director Gene Sperling, and chief of staff Jack Lew.

Former Democratic presidential nominee Sen. John Kerry of Massachusetts is playing Romney in the mock debate sessions.

They are expected to help Obama hone his stylistic presentation on stage - cultivating an image of a strong and forceful, not passive, candidate while avoiding the appearance of irritation or impatience, which has been a pitfall in the past.

"He's got to relax. He's got to show it. He's got to show a little sense of humor," former Democratic National Committee chairman and presidential candidate Howard Dean said on ABC's "This Week." "He's got to show why he's likable."

Aides said the president will also be working on speaking more concisely, curbing his tendency to be long-winded. But they noted he would not be explicitly developing "zingers and special lines," which Romney was said to be practicing, according to the New York Times.

"[President Obama] has a tendency to give longer substantive answers, it's just his nature," said campaign spokeswoman Jen Psaki. "That's something clearly we're working on."

Psaki said the president was approaching the first debate as an opportunity to "continue his conversation with the American people," suggesting he may try to avoid initiating direct confrontation with Romney.

"This will be a very large audience," she said. "He wants to speak directly to the families, the people on their couches at home, having snacks, drinking a beer, drinking a soda, whatever it is, and tuning in for the first time."

The president will spend much of the next few days in seclusion, with no public events on his schedule. However the Obama campaign hinted that he would be making some local stops to meet with voters in this critical swing state ahead of Saturday's registration deadline.

"I expect as he visits local shops the next few days he'll be spending some of his own money," Psaki said.

Meanwhile, advisers to both sides continue to downplay expectations for the performance on their candidates - with one exception: Republican New Jersey Gov. Chris Christie.

"Every time Mitt Romney has been confronted in this campaign with one of these moments, he has come through in the debate and performing extraordinarily well," Christie told ABC's "This Week," raising the bar for his candidate. "So I have absolute confidence that, when we get to Thursday morning … all you're going to be shaking your head, saying it's a brand-new race with 33 days to go."

The Obama campaign pounced on the comment, saying that the polls will be the real indicators of a "game-changing" moment, suggesting that they believe them unlikely to swing dramatically.

"When they say this will be a game-changing performance and this will change the course of the race. The facts you have to look at are where do the polls stand come next Friday, Saturday and Sunday in places like Ohio," said Psaki. "Is it a 2-point gap? Is it tied? That's what game changing means, not the kind of zingers that you deliver on Wednesday night."

Romney arrives in Denver today to begin his final preparations. He is joined by Sen. Rob Portman of Ohio who is playing Obama in mock debate sessions.