Why Trump has a hard row to hoe:
He needs 1237 of the 2472 delegates available to secure nomination.
But there are 437 unpledged delegates that go to party insiders. 150 of them go to individual state party apparatus.
If the rest of the 437 are also party insiders, that would make it unlikely Trump will get any of the unpledged delegates if it is a close nomination.
So Trump needs 1237 of the remaining 2000. That's about 60% of the total available. And as has already been noted, many states are going proportional delegate awarding and not winner take all. This makes it all the tougher. Really tough.
If nobody gets 1237, we'll have the spectacle of the party insiders running a brokered convention. And when the most popular candidate in the party has a difficult time getting to the required number of delegates, it's starting to seem like a reasonable possibility.
http://davidstockmanscontracorner.c...re-the-donald-and-the-gop-establishment-four/
Of course if he doesn't get the nomination, he could always say he hasn't been treated fairly and go third party. That pledge he signed isn't worth the paper it was printed on since party insiders have also talked about third party if Trump wins the nomination.