Take for example Dr. Ben Carson. It's pretty obvious that many conservative media and social organs like him, and no doubt that he might well be a good right winger. Yet it's quite easy to say the right things to an audience which you're trying to cater to. But can you actually translate that into good use of real power?
That's a very difficult thing to do. Outside of the political structure one can say whatever they want. Inside the structure, when there are hundreds of elected officials many of whom are working at cross purposes to you, and millions more bureaucrats who can effectively stymie your efforts, well, how effective can you be?
This is not to let politicians off the hook. When you pledge something you must do your best to make it work. Yet all too often the invariable compromises move you father away from your mark. And that's before the courts allow minority opinions to block your way too. It makes one wonder whether, as many libertarians assert, voting is worth it.
It is, but only because the alternative of long range tyranny is far worse. Sometimes, however, that is not the best incentive to be a model citizen.