For some of the Republican base, I've gotta say McCain-Feingold does it for me with regard to Senator John McCain. I just heard the Fox All Stars naming McCain as the probable Republican nominee for a number of reasons including what Mort Kondracke calls the Republican law of primogeniture, which states that the guy who's been around the longest gets the GOP nomination.
Aside from the fact that said law is just a bad idea--Bob Dole, anyone?--I think McCain-Feingold is an un-American abomination. Of course, given the state of the world today, I'd probably hold my nose and vote for McCain. But I wouldn't be happy about it.