John Kerry lost the 2004 elections to the highly unpopular incumbent President Bush. He was accused of flip-flopping.

Mitt Romney, and ex-pro-choicer, champions the pro-life cause in an effort to win the social conservative vote. He is losing to consistent, yet oft-accused of being too liberal, John McCain.

Barack Obama, while running for the US Senate in 2004, said he believed in the decriminalization of marijuana. Now, while running for President, he declares that it is not a good idea.

How much does flip-flopping truly affect one's chances at election? Thoughts?