Other extreme isn't so hot either.
It's painfully obvious that Hillary Clinton, as just one example, does not have a single fixed principle that she wouldn't drop like a hot potato if it served her ambitions. It's what you do when your principles and the polls go in different directions that makes the difference.
Bill was almost as bad, but had moments. I gave him a lot of points for pushing NAFTA when the Democratic base wasn't keen on it.