Talk politics.

That's the nature of a "headless" political organization such as the Tea Party. Since there's no central authority you can go to to find out what the goals of the movement are and aren't, there is no way to hold any of its members accountable to those goals - you can't keep anyone on-message when there's no message. The result is a kind of ideological deniability: you can get elected on what are popularly perceived to be the "party's goals", and when you stray from them, no one gets to say "but what about the tea party message?"

This is also why the party benefits from having racist jerks show up to the protests (who, i hastily acknowledge, form a small minority of those in attendance), and everyone else seems happy to let the jerks inflate their numbers, but acts blithely as if those same jerks don't reflect badly upon the movement as a whole. They're having their cake and eating it too.