Simply put, he knows too much for snappy hockey-mom images and I-put-it-on-eBay sound bites as answers to serious questions. Three decades of real experience will weigh him down in what viewers expect to be a mud-wrestling match.
What to do? Joe Biden is caught between the devil (looking mean by showing up Sarah Palin's ignorance) and the deep blue sea (appearing to be an elitist know-it-all by ignoring her and giving serious responses on policy issues).
In a political moment when America is faced with economic tragedy, the Vice-Presidential debate tonight is set up to be a farce, and Biden seems to know it.
"If it's going to get down to who can deliver the toughest lines, then she's going to win the debate," he says. "But I'm not going there."
If so, the entertainment value of the show will suffer, and for voters who love "American Idol," it will be a test as much as it will be for Biden.
Obama's campaign adviser David Axelrod predicts: "I don't think he's going to go after Governor Palin. I think he's going to make the case for Senator Obama."
But against an adversary whose only strength is pit-bill tactics with a lipsticked smile, can Joe Biden stay positive and prevail?