The most pressing question that Joe Biden faced, heading into Thursday night’s debate, was a tricky one: How do you handle an opponent who’s going to be lying his well-defined buttocks off for 90 minutes? The lack of a strategy for dealing with serial dishonesty had left President Obama dumbfounded in his first debate with Mitt Romney. He shouldn't have been taken aback: The Republican ticket-mates know perfectly well that being honest about their policies and platform would make it impossible for them to win a general election. You can’t advocate deficit-reduction and a $5 billion tax cut and a few extra billion in defense spending and be up front about what all that would actually mean—or whether it’s even mathematically possible.

Vice presidential debates are usually mere sideshows. But tomorrow’s face-off in Kentucky might be quite different. Barack Obama’s disastrous performance last week was the boost Mitt Romney needed to erase the president’s post-convention gains and turn the race into a genuine toss-up. The Republican has the momentum, and he’s shifted to more moderate rhetoric in an attempt to appeal to independent and undecided voters. Obama doesn’t get another crack at Romney until next week, so it’s up to Joe Biden to stanch the bleeding and resuscitate Democratic hopes.