They can keep him off the primary ballots in several states. I dunno, maybe he should sign it with some stipulations. Just because he doesn’t run 3rd party and says he will support the other person doesn’t mean he has to stump for that candidate. There are several I know he wouldn’t want to back - such as Jeb, Paul, Perry. They don’t want the party split and lose to Hillary - which is a legitimate concern. Perot did it, and we ended up with 8 years of the criminal Clintons. I would want assurances that the RNC will support Trump 100% should he win the nomination - that could be his counter offer - not to pull shenanigans with the delegates either.
....If Hillary becomes the frontrunner. With Obama giving his blessings to Biden to run if he decides to run, it could mean Obama will throw Hillary under the bus.
They won’t support him, pledge or no pledge. He should just lie if he really plans to run 3d. But I don’t think he will. I think he wants to rub the GOP’s nose in this as much as he wants to win.