I've read a lot of comments blasting various Republican and Democrat congress critters on their support or opposition to various bills--and inevitably each of these comments are black and white: the latest being the Democrats almost universally opposing support for Justice Alito. Voting against Justice Alito after voting against a fillibuster was a guaranteed loser vote anyways--but still people are pissed at the Democrats.
But while politics is a full body contact sport, politics is also a sport played best by having a public face and a private one. And I can see how one's private face (meaning one's own principles and beliefs) may be rendered by a public face that is the complete opposite.
Here's how that could happen.
If I were elected to congress, I would go there with a handful of principles I firmly believe in. I would also go there with certain areas of the law which I firmly support or advocate, and areas which I honestly couldn't care about.
To make this more complicated, there are areas which I may agree with my party, and there are areas where I may completely disagree with my party. Worse, some of those areas my voting constituants agree with, and some which they disagree with. And on top of that, there are areas where there is support in congress, and areas where there is no support for it in congress.
Let me take a concrete example. I firmly believe in abortion choice. That is, I firmly believe that in the first trimester, women should have the right to make the decision to get an abortion based upon their own conscience, and not have their decision made for them by fiat by the government. Now after the first trimester, like most Americans, I become increasingly uncomfortable: by the time we hit the eighth or ninth month, unless we have a "drowning pair" scenario (where two people are drowning but you can only save one), there is absolutely no reason why such a fetus (really, a viable infant in the final stages of fetal development) should ever be aborted.
Now I also firmly believe that abortion is one of those issues that are not going to fundamentally change. That is, the makeup of the Supreme Court nor the makeup of Congress will ever change the current legal landscape when it comes to abortion. Abortion rights has become, for all intents and purposes, a "fund-raiser issue"--that is, an issue which is used to scare supporters into writing large checks. But even with a majority of congress and the president all working for the same party that opposes abortion, and with a supreme court that may nominally oppose abortion, somehow they never get around to doing more than talking about eradicating abortion.
Fundraiser issues are like that: they're presented as big, scary things that you need to fork out a few hundred bucks or a few thousand--but for some reason nothing ever changes. Ever.
With that said, my own personal support for abortion rights doesn't matter one whit in terms of changing or affirming the legal landscape. It's an issue I personally feel strongly about--but my feelings don't matter. And so, it's an issue that I'm safe flip-flopping on. If I were running as a Republican in a conservative state, I'd go out and present an anti-choice face--because it helps me raise money, it's my party's position, it's my supporter's position--and more importantly, it doesn't mater at all what my public face is, the law is not going to change.
Oddly enough, such a position allows me to sabotage any real effort at abortion reform laws--and keep people talking, rather than acting.
Is it any wonder that both Bushs (Bush 41 and 43) were pro-choice prior to reaching public office, and extremely anti-choice once they got into the limelight--yet, for all their anti-choice support, nothing has changed?
Politics are never black and white. The public face doesn't have to match private beliefs, and oddly enough, presenting a public face can often aid one's private agenda. And while that may sound horrible, it's the nature of the beast: ultimately politics is about power, and about the power for one to be an advocate of one's closely held beliefs.
The only thing you can do to gain a metric as to the politican you vote for is try to find out if they have any core beliefs. And if they do, realize that sometimes political realities means one may have to present a face that violates those core beliefs.