Charges of flip-flopping do play a big role--perhaps too much--in the rapid response operations of both campaigns. There are obviously a lot of reasons a candidate might alter his position that have nothing to do with political opportunism. After 9/11, for example, President Bush's foreign policy changed in a dramatic way. I don't think anyone--save perhaps Ron Paul--implored President Bush on 9/12 to stick with the neo-isolationist talking points of his campaign. Flip-flopping is very relevant, however, when it demonstrates a candidate either doesn't know what he believes or is willing to set aside any conviction for political advancement.
In Obama's case, I'm not sure which is true, but it is patently obvious from the speed and frequency with which his flip-flops seem to come that principle is not playing any role. Just consider his evolution in a single month: Obama opposed welfare reform, and now he supports it. Obama supported the D.C. handgun ban, and now he believes it was unconstitutional. Obama said he would accept public financing, and now he won't. Obama opposed immunity for telecommunications companies involved in terrorist surveillance, and now he supports it. Obama opposed the death penalty in all cases, and now believes it is justified in certain extreme instances. Obama supported immediate withdrawal from Iraq, and now he'll listen to the commanders on the ground if they tell him to phase out the troops slowly.
Nothing has fundamentally changed with any of these issues. The only thing that has changed is that Obama became the presumptive nominee. Andrew Sullivan says, "Sometimes a flip-flop is a sign of real maturity in a politician responding to new events or facts." That's only true however, when a candidate acknowledges and explains why he's changing. Principle plays no role when the pol instead self-righteously asserts that there has been no change at all, and it also doesn't play a role when a candidate claims that everyone simply misunderstood his previous position--as with the meaning of "negotiate with Iran without precondition"--even when the so-called misperception was widely reported and the candidate did nothing to correct it for many months.
Aside from charging the other side with flip-flopping, one other job typically assigned to a campaign's war-room is correcting media reports that mischaracterize their candidate's position. That Obama's staff was apparently sitting on its hands shows Obama either meant what he said or wanted people to believe that he did.
