Four Weeks To Go

With exactly four weeks remaining in the presidential campaign, Democrat Barack Obama and Republican John McCain will face off tonight in their second debate.

The two candidates last met in their first debate two weeks ago in Mississippi, but Tuesday night's debate is expected to draw a larger audience because the first debate took place on a Friday.

The second debate -- held tonight in Nashville, Tennessee -- will also feature a change in format from the first debate, which allowed the candidates to stand safely behind podiums. Tonight, in contrast, the candidates will sit on chairs in a national town hall meeting of undecided voters. Tonight's debate moderator, NBC's Tom Brokaw, will facilitate the discussion and will also take questions from the Internet that have been sent in by email.

With the focus on the economy in recent weeks and with a still volatile market on Wall Street, Democrats are hoping that the issues will help Obama. But Republicans are hoping that the format will cater to McCain, who is comfortable with town hall meetings and holds them regularly on the campaign trail.

McCain also called for a series of town hall style debates to take place throughout the summer and Obama initially indicated that he might be receptive to the idea but later rejected the proposal. McCain is likely to bring up Obama's rejection of the proposal in tonight's debate.

Although interest in the campaign has been intense, it's not clear that tonight's debate will draw more viewers than last Thursday's widely watched vice presidential debate between Alaska Governor Sarah Palin and Senator Joe Biden of Delaware. About 70 million viewers reportedly watched last week's debate.

With the campaign grinding down to its final four weeks and polls showing Obama pulling away into a commanding lead, the McCain campaign is eager to find another "game changer" that will put the Arizona senator back in the race. Experts disagree on the expected tone of the debate, with some pundits predicting a nastier, more negative McCain will emerge, while others warn that it may be difficult for either candidate to "go negative" in front of undecided voters.

In the meantime, both sides are taking off their proverbial gloves on the airwaves this week. McCain's campaign is attacking Barack Obama for his former association with William Ayers of the Weather Underground. But the Obama campaign hit back this week with an attack on McCain's association with Charles Keating of the "Keating Five" scandal.

Whatever happens, Americans will be watching closely.