I have to admit I was impressed when all those republicans revolted during the bailout saga. I may not agree with the principles at work but I have to admire people who stuck by theirs even as their own president and candidate pointed at the falling sky.
Of course, then somebody offered them some candy and they happily climbed aboard. So much for principles. Oddly, though, Senator McCain claimed to be the one who convinced them. If we were writing this as a movie we might say that the character isn't tracking. And if a character isn't tracking in the third act, you usually have to go back to the first act to find out why.
"I'll take this old ink pen and every single pork barrel earmark bill that comes across my desk as president, I will veto it, I will make them famous and you will know their names."
Well, he didn't make them famous, did he? Not the members of either party who shoved their crap into this bill. See the problem? You can't really have your character say that line and then a few scenes later have him sign a bill called the Emergency Economic Stabilization Act, which is bloated with an additional $150,000,000,000 for things like tax breaks for a certain type of wooden arrow, rum importers, race track facilities, Exxon-Valdez plaintiffs (I'm not making this stuff up), and film and TV production (sorry guys, that shouldn't have been in there either).
Yes, Obama also signed the bill. The difference is that Obama hasn't continually claimed that eliminating "pork" is the remedy for all that ails us. He also didn't claim ownership over that bill the way McCain did.
There's another rule in screenwriting that applies here. If you have a character violate his own code of principles, he has to pay for it. For two whole movies Michael Corleone made his family his primary motivation. Then he killed Fredo and lost his soul.
McCain claims that country is his motivation for everything. Admirable. But you can't say "Country First" and then pick an imbecile to help run said country during its toughest times.
You can't say "Country First" and then employ a campaign strategy that shamelessly resurrects said country's shameful history of racial tension in order to divide it against itself.
You can't say "Country First" and then allow your running mate to tell reporters how happy she is to be cleared of "even a hint of unethical behavior" when referring to a report which condemns her unethical behavior.
Again, if the character violates his own principles he has to pay for it. That usually happens in the third act. If we're doing our job as screenwriters the character can't win. And in the denouement we must leave him with the residue of his own undoing.