As a purely political question, it occurs to me that just about the last thing you want if you're John McCain and have just flip-flopped on offshore drilling is to have President Bush perform an identical flip-flop immediately afterward. Whatever theoretical boost the position may give you is not only undercut by the flip-flop charge, but also opens you to another round of in-lockstep-with-Bush stories.
Moreover, as an electoral matter, this seems like an awfully risky move for McCain. Offshore drilling may be popular nationally, but it's long been considered a political third rail by both parties in Florida, a state without which it will be incredibly difficult for McCain to win the presidency. It may be that, confronted with $4-a-gallon gas, Floridians will be more open to the idea than in the past. Governor (and McCain veep hopeful) Charlie Crist is gambling that they will be, and Senator Mel Marinez is considering following suit. But it is a gamble, and one that McCain--down 4 points in Florida in today's Quinnipiac poll--can't afford to lose.