US President Barack Obama is under heavy pressure in his debate rematch with Mitt Romney to turn in a more forceful performance.

He needs to restore his momentum and draw sharper policy differences with his Republican challenger.

Mr Obama will try to make amends for his listless and heavily criticised showing in the first debate when the rivals square off in a nationally televised town hall setting.

This debate gives undecided voters in the audience the opportunity to question the candidates.

With just three weeks left in a deadlocked race for the White House, the President cannot afford to fumble another chance to make the case for his re-election and to blunt the rise of Mr Romney.

Political scientist at North Carolina State University Andrew Taylor said almost all of the pressure will be on Mr Obama given how poorly he performed in the first debate.

He said: "Obama has to steady the ship and instil confidence in Democrats again."

Mr Obama's passive performance in the 3 October debate launched a Romney surge that now has the two candidates running virtually even in most national polls before the 6 November election.

A Reuters/Ipsos online tracking poll yesterday showed Mr Obama with a two-point lead over Mr Romney, 47% to 45%, meaning they are essentially tied.

Mr Obama and his campaign advisers have promised that a more engaged candidate will show up in the 90-minute debate at Hofstra University in New York.

For Mr Obama this time around, the challenge will be to confront Mr Romney on the issues without seeming nasty or too personal.

Mr Romney, a 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.

Not only have his overall poll numbers improved since the last debate, but personal approval ratings have also crept up.

Both men will have to deal with the more intimate town hall format, which often inhibits political attacks as the candidates focus on connecting with the individual voters who ask the questions.

Both candidates have taken time off the campaign trail to prepare for the showdown, the second of three presidential debates.

The final one will be Monday 22 October in Boca Raton, Florida, and will focus on foreign policy issues.

The debate will be shown live on RTÉ News Now at 2am. Replayed at 9.05am.