US President Barack Obama and his Republican challenger Mitt Romney on Wednesday began their first presidential debate at Denver University in Denver, Colorado, with the debate focusing on economy and domestic issues.

The debate, hosted by veteran PBS journalist Jim Lehrer, started off with a question to Obama on how he would create jobs. Obama answered it for two minutes, then Romney took his turn.

The debate is to run for 90 minutes.

Economy is the most important topic, as it takes up half of the time.

Prior to the debate, both campaigns had said it would give the candidates an opportunity to speak directly to voters without the filter of the media.

The debate has higher stakes for Romney, as he is trailing the president in polls. Ben Ginsberg, a top Romney campaign aide, said Wednesday morning at a Denver briefing that the former Massachusetts governor will try to showcase his contrast with Obama in their visions for America for the next four years.

There is some unfavorable buzz against the Obama campaign heading into the debate. Vice President Joe Biden, a top Obama surrogate, said Tuesday that the middle class had been "buried" during the past four years, a statement that Republicans immediately seized upon as an unwitting indictment of the Obama presidency.

A 2007 videotape of then-Senator Obama, which showed him making comments perceived as "racially charged," also surfaced Tuesday night, rocketing through conservative media outlets.

However, Obama is still going into the debate with a clear advantage in polls, and about two-thirds of the voters believe Obama will win the debate.

But Obama's lead in the presidential race is being challenged, as most recent polls show Romney is closing the gap somewhat.

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