As a maverick Republican, willing to work across the aisle on legislation, he is treated like a king by hopeful Democrats. And, as a dissatisfied Republican, who might any minute walk away, he is romanced by nervous Republicans. He's got everything going for him. Short of the White House, McCain will never have as much power. It makes no sense for him to change now.
Timing is everything in politics.
McCain's best move now is simply to wait. Wait and watch. Wait to see how well Bush does. Watch to see if he signs the McCain-Feingold legislation, supports a patient's right to sue HMOs or challenges the NRA on gun show loopholes. And, perhaps most importantly, watch to see if Bush ever wakes up to what's happening in other parts of the world and exercises his responsibility as world leader.