Huck can't win.
The big question is, that being true, what is his angle?
I believe he can still win, although it would be a long shot. Viriginia has a winner take all primary 63 delegates, while a big win in TX and OH could really boost his count. Throw in that he will do well in the other smaller states and I think he can make up substantial ground and go to the convention with neither he or McCain as the outright nominee.
If he wanted VP, he would just get out now that Mitt is out and claim his prize.
Actually, McCain has to win 40% of the remaining delegates to secure the nomination outright. The lion’s share of his support came from big, dumb blue states (New York, New Jersey, California) - but they’re over, from here on out we get a bevy of red states where he simply doesn’t have that much appeal.