Bush's personal approval in danger?

Yuval Rubinstein (of the left coaster) makes a couple of cogent point about Bush's recent attacks on Kerry: (1) they are a sign that the Bush campaign has run out of ammunition to run on (economy, foreign policy, etc.) and has to rely on a character debate and (2) by attacking Kerry directly Bush risks hurting his own personal approval ratings.

This is similar to the point I made in my previous post about how an ugly fight between Kerry and Bush will almost certainly drive down both candidates personal approval ratings. What I hadn't considered in that analysis was that Bush's personal approval rating is all that Bush really has going for him. Kerry, at least, has the advantage of being "a change" and, when things turn ugly, people are more open to the idea of voting for "a change".