Expectations game in full swing for US presidential debate

The Democratic incumbent and the Republican former governor of Massachusetts face off in Denver, Colorado, on Wednesday for their first of three televised debates.

Advisers to both men have tried to lower expectations for their respective candidates, and Obama got into the action during a rally in Nevada.

"Gov. Romney ... he's a good debater. I'm just OK," the president told a crowd of about 11,000 outside a local high school.

"What I'm most concerned about is having a serious discussion about what we need to do to keep the country growing and restore security for hard-working Americans. That's what people are going to be listening for," he said.

New Jersey Governor Chris Christie predicted fellow Republican Romney's performance would alter the course of the campaign. Polls show Obama with a slight edge nationally and in critical swing states that will decide the November 6 election.

"This whole race is going to turn upside down come Thursday morning," Christie told CBS' "Face the Nation."

His comments strayed from the script of both campaigns, which have tried to play down their own candidate's chances and talk up their opponent's, thus making it easier to claim victory or explain a defeat after the face-off.

"I think what we need is a big and bold performance on Wednesday night, and that's what he's going to give us," Christie said of Romney on ABC's "This Week."

Romney comes into the debate still trying to recover from a leaked video where the former private equity executive described nearly half of Americans as dependent upon government and who view themselves as victims.

"We've had some missteps, but at the end of the day, the choice is really clear," Romney's vice presidential running mate Paul Ryan told "Fox News Sunday."

Ryan tried to lower the stakes for Romney's debate performance. "I don't think any one event is going to make or break this campaign," he said.

Ryan said Romney would give a major foreign policy speech in the days after the debate.

Obama's advisers said the president was not focused on scoring points or coming up with zingers to use against his rival.

"He wants to speak directly to the families - the people who are on their couches at home, having snacks, drinking a beer, drinking soda, whatever it is, and tuning in for the first time - and that's who he's speaking directly to," campaign spokeswoman Jen Psaki told reporters on Air Force One.

Obama, who is in Nevada for intense debate preparation, was accompanied by White House adviser David Plouffe, campaign strategist David Axelrod, chief of staff Jack Lew, economic adviser Gene Sperling and speechwriter Jon Favreau.

The White House and Obama's campaign are guarding against complacency, despite their strength in the polls.

"We're not going to win battleground states by 10 or 12 points. This race is going to tighten," Plouffe said on NBC's "Meet the Press."

Romney remained in Boston for private meetings, including debate preparation, at his campaign headquarters.