Veeps Matter -- Except for When They Don't

Rob is right that veeps don't matter -- except for when they do. Yes, not even Dan Quayle could sink George H.W. Bush, but that's because he was running on Ronald Reagan's coattails. Bush also had the good fortune of running against the pathetic Michael Dukakis.

Other veeps have made a big difference. Walter Mondale, Al Gore and Dick Cheney all brought D.C. street cred to their outsider running-mates. LBJ and Bush Sr. unified shaky coalitions -- which can be priceless if it frees up the candidate to focus his efforts on swing voters.

Such gains are hard to detect, but meaningful nonetheless. What's most important at this stage is that no one bungles his pick. Could you imagine if Obama had chosen John Edwards?