This is the dilemma facing John McCain heading into tonight's town hall debate. Should John McCain, sliding quickly in the polls, go after Obama with questions about his background and personal associations - questions the McCain campaign has made clear it plans to raise for the remainder of the race. Should McCain follow Palin's lead and unload an Ayers/Rev. Wright/machine-politics missile at Obama in the hope of raising fear and unease about a candidate much of the public still knows little about.

The problem with such an attack, described well today by John Dickerson at Slate, is that McCain runs the risk of being criticized by an audience member (during the audience's question-answer segment) for going negative and not focusing on 'real' issues. Such was the circumstance for George H.W. Bush in the 1992 town hall debate. As Dickerson puts it, "You don't want Joe Six Pack calling you out."

The McCain camp has to assume that tonight's audience members have not been living in a box for the last few days. They know of the McCain camp's new strategy to go negative - and perhaps there's an Obama-leaning member of the crowd who wouldn't mind humiliating McCain with a devastating zinger. Such an attack from a 'Regular Joe' in the audience, rather than an 'elitist' reporter, would be a disaster. Furthermore, David Axelrod announced today that should McCain unleash a personal attack, Obama will be ready with a counter punch.

But perhaps this dilemma for McCain has been oversimplified by the media. There is a third route McCain can take tonight. If we assume it is too risky to attack Obama on Ayers, Wright, etc., and we assume the McCain campaign is not dumb enough to play this debate straight-laced with simple policy answers to Tom Brokaw's questions, then McCain is left with the possibility of combining these two strategies together.

McCain should be on the attack from the get-go on every policy question he receives, pounding Obama relentlessly. With each question, McCain can time and time again bring up a specific scenario in which he himself worked across the aisle to get something done. The attack will be the tricky part.

The McCain campaign seems to believe that their sole challenge is to attack and change the subject from the economy. But what McCain also needs to drastically improve is the cohesion of his attacks. As James Carville noted this morning on Good Morning America, attacks from McCain and the rest of the campaign have been flying out from all different directions. Obama is either too liberal, too inexperienced, has relations with despicable people, or lacked good judgment on the surge, etc. There simply hasn't been a core theme with which these attacks can be unified into a core case against Obama.

If McCain is to be effective tonight he will pick one overlying theme with which to hit Obama. For example, experience. With each question McCain answers he needs to show why his experience will make him the better president and why Obama's lack of experience would make his Presidency a disaster.

Steve Schmidt has not received the amount of credit he deserves for turning around what was only a few months ago an abysmally dysfunctional campaign. But Schmidt has not solved the message problem. While David Brooks and other conservatives have argued that McCain lacks a unifying economic and policy message as well, McCain needs to use a core attack message unrelated to the personal attacks of late. Voters need to leave the debate with a specific reason for uneasiness about an Obama Presidency lingering in their minds.

If Obama comes away the clear victor tonight, this race is likely over.

Greg Bobrinskoy is an Associate Editor at RealClearPolitics