I'm not a Bush supporter and will probably vote Kerry despite my status as a Republican--I'm not impressed with either, so I'm willing to give the new guy a chance, and (blasphemy coming, fellow Republicans) I think that Dems are better on the economy. But honestly, this kind of stunt would push me the other way, as it would anyone who didn't already agree.
ETA: Apparently, the argument goes that this is based on the Declaration of Independence stating that we should have a "decent respect for the opinions of mankind." I get a kick out of that, as the point of that statement was not to solicit said opinions, but to concede the point that the rest of the world might not immediately understand why a rasonably affluent bunch of colonies was telling George III take his toys and go home, and would appreciate an explanation of said decision. The Founding Fathers were not actually planning to open an international debate on the subject.