Given his personality type, I think he is exhibiting signs of intense frustration that comes from the diminishing amounts of undeserved adulation he received during his primary run. And that may very well lead him to simply take his ball and go home. That decision could be further accelerated by a GOP that is now having a rather serious case of buyer's remorse.

Trump recently told serious supporters that his surrogates were wrong to downplay his criticism of the judge overseeing the Trump University trial, according to a Bloomberg report. Trump apparently said that he felt his surrogates ought to continue the attacks and go after journalists, suggesting that they are the true racists in this scenario.



Potential vice president picks, like Newt Gingrich and House Speaker Paul Ryan, have criticized Trump for his unusual attacks on Judge Gonzalo Curiel. Gingrich went so far as to say that Trump referring to the judge's ethnic background as a conflict of interest was "inexcusable" and "one of the worst mistakes Trump has made."



More worrisome is the anger and vitriol being spewed by the candidate as the going gets tougher. Former Secretary of State Hillary Clinton's foreign-policy speech appeared to get under his rather thin skin, and prompted responses from Trump having nothing to do with a substantive rebuttal. That could be a preview of how he'll handle Clinton in one-on-one debates. Further, the prospects of Trump whiffing on policy issues while Clinton riddles him with facts could seriously harm the GOP's image and fatally wound down-ballot candidates.



Trump's presidential obituary has been written more than once, and prematurely. But there seems to be a change in the air. His behavior is more erratic. Republican leaders appear to be backing away from him, fearing a voter backlash if they stand too close to someone who, until recently seemed only toxic, but may now be radioactive.



Trump appears ready to cross a line that may cause his reluctant GOP supporters to flee, lest they lose the Senate, the House, and maybe even the party.



His invective is taking on a new intensity as he struggles with the personal and political scrutiny that comes with being the party's standard-bearer. It might be too much for even Trump to bear. He is accustomed to unflagging support, idol worship and winning.



Trump may have to choose between two outcomes that are not only wildly unpalatable, but two descriptions that he uses to belittle others: Quitter or loser.



It seems the master has become the apprentice and in this case, he may find himself fired by the people who reluctantly just hired him. It will take some Machiavellian maneuvers, but I wouldn't be surprised if Trump is soon off the stage.



The Clinton camp may need a Plan B just in case they find themselves facing a different contestant come November.



Commentary by Ron Insana, a CNBC and MSNBC contributor and the author of four books on Wall Street. Follow him on Twitter @rinsana.



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