Boss
Take a Memo:
Not only does he have an oversized ego, he's also got a whole lot of money, so if the GOP doesn't pick him, it would be easy for him to switch over to Independent and keep running his campaign.
That would almost surely result in a definite win for the Democrats.
You know... I am not so sure at this point.
I think Trump would almost certainly not run as a third party candidate, especially if another conservative wins the nomination. But if Trump wins the GOP nomination, I can see some idiot like Kasich going 3rd party to upset Trump. I think THAT is the more likely 3rd party scenario.
Now... Let's say that the GOP convention is a "brokered" convention and we roll into it without knowing for sure WHO the candidate will be, Trump or say... Jeb Bush? The smoke-filled backroom deals will be made and Trump, even though he has the most delegates, gets nuzzled out for Jeb as the nominee. In THAT scenario, you might very well see a Trump 3rd party candidacy... AND... He will WIN!
I think, under the above described scenario, you would get to witness the demise of a political party. Trump would pull not only the majority of republican votes, he would also pull a good many democrat votes.. He almost certainly WILL pull democrat votes, regardless. Trump would NOT have to have a majority to win... several presidents, including Bill Clinton, were elected president without a majority. He would finish ahead of Hillary and Jeb would be sucking hind teat.