Romney's campaign got a much-needed shot in the arm two weeks ago when the Republican came out swinging in the first matchup between the two candidates, while Obama appeared passive and tongue-tied at times.
The strong debate performance helped Romney reverse his slide in the polls. Recent surveys put the race for the White House at a virtual dead heat with just three weeks left before the November 6 election.
"I think you'll see somebody who will be strong, who will be passionate, who will be energetic, who will talk about ... not just the last four years but what the agenda is for the future and how we continue to move ... our economy forward," Obama's senior campaign adviser Robert Gibbs said on MSNBC.
The 90-minute debate at Hofstra University in New York begins at 9pm EDT (0100 Wednesday GMT).
Both men will have to deal with the more intimate town hall format of the debate, which often inhibits political attacks as the candidates focus on connecting with the voters asking the questions.
It also offers an element of uncertainty as the candidates cannot predict what the audience of undecided voters might ask, which could range from tax policy to job creation to foreign policy.
"It enables them to talk directly to people and look them in the eye and try to connect, which has not been a strength for either of them," Taylor said of the town hall format. "But you can still make strong points with a velvet glove."
During the first debate, Obama was widely criticized for not challenging Romney on exactly how he plans to give Americans a big tax cut without adding to the deficit, and for not calling attention to the more moderate views Romney appeared to present during the matchup.
"Almost all of the pressure will be on Obama this time, given how poorly he performed in the first debate and how much that seemed to help Romney and change the race," said political scientist Andrew Taylor of North Carolina State University.
A Reuters/Ipsos online tracking poll on Monday showed Obama with a 2-point lead over Romney, 47 percent to 45 percent.
A Gallup/USA Today poll published on Tuesday showed the two had similar favorable ratings from registered voters. But the survey showed Romney ahead of Obama by four percentage points among likely voters in the 12 battleground states.
For Obama, trying to repair damage from the last debate, the challenge will be to confront Romney on the issues without seeming nasty or too personal.
Romney, a wealthy former private equity executive often accused of failing to connect with ordinary people, would be happy with a steady performance to keep up his momentum.
