The GOP presidential front-runner has come under fire from all directions for his most controversial proposal yet: banning all Muslims from entering the United States
. The idea, coming on the heels of a mass shooting in San Bernardino
, California, has deeply alarmed Republicans already on edge about the permanent damage Trump's candidacy will leave on the party.
Earlier this year, Trump met with the head of the Republican National Committee in New York and signed a "pledge"
vowing not to run as an independent and support the party's eventual nominee.
But in recent days, Trump has started to backtrack.
He said an independent run was "highly unlikely" in an interview with CNN's Don Lemon
on Wednesday, but declined to completely rule it out, calling the pledge a "two-way street."
"If they don't treat me with a certain amount of decorum and respect. If they don't treat me as the front-runner ... If the playing field is not level, then certainly all options are open," Trump said.
So what would a third-party run look like? Is it even feasible? Here is CNN's guide:
When's the deadline?
Trump still has some time to make up his mind -- but not that much time.
One of the most significant hurdles for launching an independent bid is gaining ballot access in every state -- an arduous process that involves gathering lots of signatures, fast. The earliest deadlines are in states like Texas, where independent candidates need to get on the ballot by next spring.
That means Trump realistically has to start the process of launching a third party bid by no later than March, experts said.
"The decision will need to be made sooner rather than later because of the ballot deadlines," said Clay Mulford, who advised Ross Perot's third party run. "You'd really need to get started no later than probably the beginning of March."
And in theory, Trump could also seek the nomination of an existing minor party that already has some ballot access such as the Libertarian Party. But it's not clear that any third party is a natural match for the kind of campaign that Trump has been running this cycle.
Is it doable?
Successfully launching a third-party bid is complicated and tedious, but it's definitely doable -- especially if you have money.
Trump would need to dig into his wallet to build signature-gathering operations and get on the ballots in all of the states -- a process that would likely cost tens of millions of dollars.
But it's not clear if the billionaire real estate mogul is really willing to shell out.
Trump has been surprisingly stingy so far this cycle. As of the last filing deadline, Trump had only spent about $2 million of his own money -- the other $4 million the campaign spent were donations from supporters.
Though he's recently talked a big game about TV ads, Trump hasn't written big checks yet to go up on the air -- he's only run radio ads so far.
If he doesn't want to spend his own money, he could start fundraising in earnest. But that would go against his promise to be a "self-funding" candidate.
How much would it hurt the GOP?
A Trump third-party run would be very bad news for the Republican Party.
Trump is fully aware of this, and it's precisely why he continues to dangle this threat in front of the party.
"If he ran as an independent, there's a really good chance that if he didn't win, the Republican would come in third place. A really good chance," said Bill Hillsman, a political consultant who has worked with numerous independent candidates.
And as harsh as many in the party have been about Trump's recent comments vowing to ban Muslims from entering the country, senior Republicans continue to check their criticism.
Republican National Committee Chairman Reince Priebus declined
to elaborate on how Trump's proposal might hurt the party, telling the Washington Examiner
: "That's as far as I'm going to go."
Even Trump rival and vocal critic Jeb Bush would not go as far as to take back his pledge to support whoever wins the GOP nomination, only saying that Trump is "not going to be the nominee."
Can Trump switch midway through the primary?
Yes -- and there's historical precedent for it.
John Anderson started running for president in the 1980 election as a Republican. In April 1980 -- after having already participated in numerous primaries -- he decided to run as an independent, and was able to get on the ballot in all 50 states.
The trickier question is what would happen if Trump decided to make the jump after having won one or more states.
Several experts speaking with CNN were divided on whether delegates would be likely to stick with Trump at the convention. This kind of unfamiliar territory would further throw the party into chaos.
So will he do it?
The best guess -- for now -- is that Trump will not.
He's said as much himself. He wants to run as a Republican, and he believes he has a better chance of winning the White House as a Republican than as an independent.
"He's doing well enough in the polls that if I were advising him, I would say, don't run as an independent. You're going to get the nomination," said Richard Winger, a ballot access expert. "I would say go full-board with what you're doing. And I'm sure that's what he'll do."
However, the one thing Republicans have learned about Trump this year is that he is completely unpredictable -- and seems to have little allegiance to the GOP.
"The Republicans ought to be taking it seriously," said Nathan Daschle, President & COO of the Daschle Group. "There are some things we know about Trump. He's concerned about himself, and he'll put his own interests way above the party's."