That’s because none of the other candidates can afford to lose another point.
There’s some state GOPe’s that are trying to attack him by tying a loyalty oath to their primary.
But Trump is so high in the polls, that I think the loyalty oath will be a nuisance, and Trump will comply. But I hope he trashes the proponents of the oaths so hard, that they leave the party.
If the states GOPe takes the most popular candidate off of the ballot, the veil will be completely off and I think that there will be a mass exodus from the GOP.