Politicians

Why is it that when a leader of a political party is the Opposition, they're all for the people and they're best interests, but once they gain power, all that is forgotten? Stupid question. The answer is obvious. But we need to remember that when election day roles around (And NO, I don't mean don't vote for at all; I mean vote for change, vote for something different. And NO I don't mean vote for Howard Galganov).
I'm looking at you Michael Ignatieff and Dalton McGuinty.