McCain's Peak?

Ross ponders McCain's poll ceiling:

But by all rights, this ought to be a peak time for McCain's numbers - not the peak, necessarily, but certainly a high point. His right-wing critics are making nice with him, his favorable ratings are sky-high, and his opponents are too busy driving each other's negative ratings upward to spend any time (or money, more importantly) putting a dent in his halo. Moreoever, the Democrats' intra-party tensions are bound to diminish once the party picks a nominee: At least some of the Hillary supporters who tell pollsters that they'd vote for McCain over Obama may actually follow through on that pledge, but a lot of today's McCainocrats will come home to the Democratic fold when all is said and done.

Yet even with all this going for him, McCain's poll numbers are bumping up against the same 45 percent ceiling that they've been hitting since December. If the election were held today - a pretty good day for McCain, all things considered - he'd probably lose to Obama, and might lose to Clinton as well. That doesn't mean he will lose, by any stretch, but it certainly doesn't bode well for November.