President Obama badly needs a debate win Tuesday in New York to mitigate growing concerns about the state of his campaign. But as Democrats clamor for a feistier showing, the president faces a delicate balancing act: looking firm but not combative.

Obama, reeling from a lifeless performance on the debate stage earlier this month, needs to convince voters that his opening rhetorical salvo against Republican Mitt Romney was simply an off night.

The easiest way for Obama to do that, analysts said, is to challenge Romney rather than letting the Republican put his stamp on every argument.

"Obama has got to show some passion, show some energy," said Dennis Goldford, a political scientist at Drake University. "He didn't show either last time. And he has to do so without letting Romney dominate the discussion."

Obama attempted last time to play it safe, but that strategy backfired, causing some to question his mettle as commander in chief.

For their part, Obama's re-election team vowed Monday the president would showcase a "firm but respectful" demeanor, a recalculation from a debate in which Obama appeared bored despite the chance to speak directly to millions of Americans in prime time.

But Obama must be careful. An all-out attack -- particularly in a more intimate town hall setting -- could alienate debate viewers and come off as a desperate ploy by a politician looking to regain momentum.

"He's in a box with this debate," said Mitchell McKinney, a political communication professor at the University of Missouri. "If he comes out guns-a-blazing, it might leave those in the crowd in shell shock. It's a difficult task to attack while seeming kind and polite -- he has to find a way to do it with some levity."

President Ronald Reagan masterfully employed such a strategy, made famous with his "There you go again" attack against Jimmy Carter. And Democratic President Clinton found a way to look strong but empathetic in similar town hall venues.

In contrast, Vice President Biden last week spent much of the night mocking and dismissing Rep. Paul Ryan, R-Wis. While Democrats cheered the pugnacious style, the performance turned off some undecided voters who considered Biden's antics patronizing toward the younger Ryan.

Obama is likely to modify Biden's debate blueprint, analysts said.

"Regular folks don't like these zingers back and forth," said Democratic pollster Mark Mellman. "Mainly, he needs to prevent Romney from having the kind of win he had the other night. But I don't think he needs a home run."

Obama whiffed last time he stared down Romney on the debate stage. And voters have given Romney a second look after he exceeded their debate expectations, easily besting the president in a high-stakes job audition.

A USA Today/Gallup poll released Monday gave Romney a 5-percentage-point lead among likely voters in battleground states, thanks in large part to gains among female voters.

But this forum is a whole new challenge for the former Massachusetts governor, who must come off as personal and in touch with the concerns of those in the debate hall and watching from home.

"Letting Romney be Romney isn't exactly enough to maximize his results in this setting," said Mellman, pointing out the Republican has yet to close his likability gap with Obama, a weakness that could be exploited by lengthy, uncontrolled exchanges with audience members.