If Trump wins the nomination, will the GOP split?

[Famous Mortimer]

There's been some talk of Trump running as an independent, especially if Bush wins the nomination.

What if it happens the other way around though?

It's hard to imagine Bush, McCain, Rubio, Graham, and several other prominent Republicans endorsing him.

Might one of them go even further and launch a third party candidacy?

How would it go down?

[RFK Jr.’s Brain Worm]

McCain is a bit too old, I think. I could see something like a Rubio/Graham ticket though. That way, it wouldn't have the Bush name that may drive away some potential voters. I might make a map later.

[kashifsakhan]

If, come late 2015/early 2016, it looks like Trump has a decent chance to win the GOP nomination, I bet a fire is going to be lit under every single Democrat primary candidate left in the field. I'd even go as far as saying a few new candidates would throw their hats in the ring with late entries into the contest because they'll all believe it'll be their best chance to win the presidency.

As far as GOP is concerned, I don't see a split happening. The GOP for all its faults and sometimes extreme rhetoric is an amazingly unified party, much more so than center-right parties are in Europe and in other countries such as Australia. The only other center-right party I can think of that backs their leader as strongly as the GOP is the BJP in India.
I think the GOP will stick to their guy, even if a few big names don't necessarily endorse Trump.

I few guys like Bush, Rubio, Christie et al will decide to stay quiet and let Trump have his go. Their thought process will be 'Let Trump have a go. He's probably going to lose, and then I can have a go at the nomination in 2020".

[andrew_c]

No.  The GOP will just let Trump sink.

[Vega]

For him to actually win the nomination, the majority of the party would have to be in support of him; so no.

[Skill and Chance]

They'd just let Clinton McGovern him, focus on keeping the House, and then use him as cover to openly tell off the Tea Party for 2018-20.

[Leinad]

Trump won't win. It's impossible. He obviously won't get any establishment support, and he's not conservative enough to get lots of those voters. Like Rand Paul, he only excels in one faction, and it's not a big enough one to get the nomination. In the Donald's case, it's dissafected voters who really hate the establishment, hate immigration, and hate "politics as usual." Some of them are ideologically conservative, but I'm willing to bet they'll drift towards a guy like Cruz or maybe Santorum (in the unlikely event that Santorum starts gaining traction). What's left is low-information voters who are just vaguely angry and might not even vote.

BUT, if you look past reality and say Trump wins, I agree with the others that 1) no serious Republican contender would show up and 2) Hillary would make him look like Brazil in the World Cup semis.

[MyRescueKittehRocks]

Trump is an establishment plant.  They're afraid more of Cruz/Paul/Walker getting it then they are Trump getting it.

[heatmaster]

Trump will be successful in one way, his candidacy will demonstrate what a big wallet and an even bigger ego can accomplish.  He is catering to the angry frustrated middle aged white guy, blaming the other person for there failures and misfortune. Nothing to contribute as far as a realistic solution goes, but always willing to sound off.