In 2002 voting against going to war in Iraq was expected to be a massive political liability.
In 2008 Barack Obama won the Democratic nomination in part because of his continuous opposition to the war. (He did vote against withdrawal in 2006 but I don't think that changes the perception that he was "against the war.")
Now in 2012 Paul Ryan went on TV and supported his claim that he has foreign policy experience by saying "I voted to send men and women to war [in Iraq]."
You get whiplash from how fast public opinion about Iraq changes.