Trump might end up a spoiler, staying on the ballot for the fun of it, and getting enough delegates to prevent anyone else from crossing the 50 percent threshhold.
There are several scenarios.
It requires that the top candidate not get 50 percent of pledged delegates. The main way I see that happening is if there's a clash between two frontrunners, with a third candidate getting some support. Huckabee or Rand Paul could easily fit that role, since they could have a strong base of support.
It is a bit unlikely, though.
The establishment would unite if somone they consider unacceptable is leading in the polls.
With Hillary and Obama in 2008, there was more of a cultural divide. It was about experience and the possibility of the first female President versus change, youth and the possibility of the first African-American President. I don't see Republicans getting as passionate about likely match-ups (Bush VS Rubio, Rubio VS Walker, Bush VS Walker.) There's likely to be a point where the frontrunner pulls away.
If the top 2 candidates are over 50%, it's all over.
If candidate 2 and 3 are over 50%, it's all over.
Trump can't force a brokered convention, but he could win enough delegates to wreck havoc on TV if the GOP gangs up on him and tries to stop him. It would be one thing if Trump has 20% of the delegates, but what if he had actually gained 40% of the delegates? It would mean that he had won most of the primaries, and had gotten more primary votes than any other Republican.
Would the GOP at that point make an accommodation with Trump? Would they decide to let him be the nominee and get him out of their hair? Because Trump, at 40% of the delegates, would be a candidate of the rank and file at that point, and any plan to preempt his nomination would infuriate many ordinary Republican voters who would view themselves as disenfranchised.
If Trump is getting 30-40% of the delegates, it means that the race has spun in a direction far beyond what the establishment planned. I've got to believe that a number of establishment types will conclude that they miscalculated, and that they shouldn't have attacked Trump so early in the campaign. They'll HAVE to "suck up" to Trump, and he might not settle for anything less than the nomination.
If Trump is denied a nomination he can be viewed as having earned, lots of bad things for the GOP can happen. Such a perception would undoubtedly elect Hillary, even if Trump were not a third party candidate. Such a result, however, would suggest that the GOP rank and file is in a different place on a whole lot of issues than people think they are.
Trump is not as far away from the GOP on issues as, say, George Wallace was far away from the Democratic mainstream in 1972. Compromise is possible, but the rhetoric against Trump has made it hard for a lot of folks to eat crow if they needed to for party unity.
