The party bosses are not happy with him. The difference in positions by all their candidates is trivial and minute. The Donald is merely louder, and less evasive. Reality and logical argument are illegal aliens to the Republican Party, so it is not the substance, but the Donald style that is the difference. The ignorant base Republican likes the Donald's brashness; they interpret it as frankness.
Where Trump is different is that he insults other Republicans, breaking Reagan's commandment, a commandment that Republicans actually believe in. Like other Republicans, he doesn't admit to facts or to error. Politic and strategic gaffes he does not recognise, they become points of honor that will be defended and advanced. What he says about other Republicans is true, and if they play tit for tat, well good. Donald will not back down.
The great stuff about the Donald is he grabs the microphone and camera, and the other clowns remain in the shadows, some trying to perform a silly antic that the audience would notice. In a few days, there is to be a Republican 'debate' on 'Fox' limited to the top ten in the polls. The press recognises sixteen candidates. The last to announce, Kasich from Ohio, received reduced attention from the press because of Trump's attempt to monopolise the spotlight. Yes, the 'debate' will be in Ohio, and the governor of Ohio may be excluded.
Even more betterer, Trump is threatening the party, that if he is not treated well by them, he will run as a third party candidate. O, please, please.
Georges Clemenceau *1841, 1929† would become premier of France twice. Long before, in 1886 under the Third Republic, he said for president, "I shall vote for the stupidest".
There is a Polish comment, "Nie mój cyrk, nie moje małpy (not my circus, not my monkeys)". Yeah, they are idiots, but not my problem.
postscriptum: the politician Trump resembles most is Silvio Berlusconi