What the Candidates Need to Do in Debate No. 2

President Barack Obama greets people as he arrives at John F. Kennedy International Airport, Tuesday, Oct. 16, 2012, in New York, en rout to Hempstead, N.Y. and a presidential debate.  (National Journal)

One night in Denver two weeks ago proved that the presidential debates can matter. With President Obama now on the defensive and Republican Mitt Romney seeking to cement his gains, here are the stakes for Tuesday night's matchup at Hofstra University in New York, a town-hall debate moderated by CNN's Candy Crowley.

ONCE MORE, WITH FEELING: After his lackluster and passive performance at the last presidential debate — deemed by Gallup the most lopsided defeat in recent debate history — Obama must bring his A-game this time. In the two weeks since Romney dominated their first exchange, the Republican presidential nominee has managed to erase Obama's lead in several national and swing-state polls. With less than a month to go until Election Day, Obama cannot afford to lose any more ground.

He will have to defend his record much more stridently this time and attack his opponent more aggressively, all the while trying not to look desperate or petty. Maybe more than anything, he just needs to show — perhaps to his demoralized supporters most of all — that he wants a second term.

KEEP UP THE PACE: By the same token, the burden is on Romney to maintain his newfound momentum. He doesn't necessarily have to best the president as unequivocally as he did in the last debate, but he is under significant pressure to turn out another solid performance, as recent polls show GOP enthusiasm cresting.

Undecided voters, however, are still seeking to learn more about the Republican challenger, and the debates represent Romney's best opportunities to connect with them on his own terms. Once again, he'll seek to appear commanding and authoritative as he shares the stage with Obama, while also relating to the concerns of average Americans.

FEEL YOUR PAIN? Speaking of Americans' average concerns, Romney's longtime liability as a candidate has long been his difficulty trying to convince voters he understands them. This debate, which will feature questions from undecided likely voters, provides a high-profile chance to prove otherwise.

The town-hall format has historically produced some of the most-memorable moments in presidential debate history. In 1992, President George H.W. Bush stumbled over a question about how the national debt had affected his life, defensively telling his interlocutor that being rich didn't prevent him from understanding the common man's difficulty. But Bill Clinton, seizing the opportunity, immediately engaged the voter and explained how he had seen the recession wreck the lives of the people he governed in Arkansas. In an election famously all about the economy, it was a moment that proved to the American people that Clinton better related to their lives.

Such memorable moments have been a hallmark of town-hall debates, according to Mitchell McKinney, a professor at the University of Missouri who has written about the impact of debate formats on presidential elections. "Our research shows in terms of citizen reaction to debates, they recall more of what happens in a town-hall debate than they do in a journalist- or moderator-directed debate," he said. "They relate more to these people. And you also often get a little bit of narrative."

LIBYA, HERE TO STAY: The terrorist attack that led to the death of the U.S. ambassador to Libya and three other Americans has fast become one of the race's most important news stories. And the White House's initial response to it, when it erroneously claimed that the deadly assault was sparked by an anti-Islam YouTube video, has only deepened Obama's political troubles.

Vice President Joe Biden's answer about Libya during his debate last week — that he was unaware the consulate had requested additional security — did nothing to put the question to rest, and it's likely Obama will face a similar query. Worth watching: Will Obama, like his Deputy Campaign Manager Stephanie Cutter, call it a political controversy manufactured by the Romney campaign? Cutter's response brought swift blowback.

At stake is the president's image as a strong commander in chief and steward of the country's foreign policy — two areas where voters generally give him high marks. How he handles the question could determine whether he keeps those advantages over Romney until Election Day.

Jill Lawrence contributed contributed to this article