As I recall it was moderate Republicans (and some conservatives, like Fred Thompson!) who allowed McCain-Feingold to go through. Not to mention signing it was GWB’s biggest mistake. So for party leaders to admit they want to undo their own legislation is pretty embarrassing. Of course another big proponent of “reform” was the defeated Rep. Chris Shays.
Remember the argument at the time? "It's unconstitutional, scotus will strike it down". So he signed it. (the "New Tone" and all that crap) What kind of conservative "constructionist" signs a bill he knows to be unconstitutional?
I do solemnly swear (or affirm) that I will faithfully execute the office of President of the United States, and will to the best of my ability, preserve, protect, and defend the Constitution of the United States.