Obama opposed the Iraq invasion as a "dumb war" that would "require a US occupation of undetermined length" and "fan the flames of the Middle East" in 2002.
Edwards too voted to authorize war; so did Kerry and others supposedly respected by Obama's campaign. Obama derides Clinton's vote only because she's his biggest competition.
But Edwards and Kerry now describe voting to authorize the war as a mistake, while Clinton continues to claim it was justified based on the information she had at the time.