The threat hangs over the Republican Party’s head with the precariousness of the candidate's own poorly constructed comb-over.
Though opinions vary on how serious he is, there is near uniformity within the ranks of the GOP that a third-party White House run by Donald Trump would consign the Republicans to all-but-certain defeat at the hands of Democratic front-runner Hillary Clinton. Public polling universally supports this thought, showing that if Trump ran as a third-party candidate, he would siphon off enough support from the eventual Republican nominee to secure the election for the Democrats.
On Tuesday, Trump shot down reports that he might rule out a prospective third-party campaign. The New York City real estate magnate and reality TV star noted during an appearance on CNN that he was leading in all of the polls as a Republican and wanted to continue running under the GOP mantle.
And then he added a big disclaimer.
“If I am treated fairly, that's the way it's going to be, but I want to keep that door open,” Trump said, in reference to a potential third-party run. “I have to keep that door open because if something happens where I'm not treated fairly, I may very well use that door.”
But even if he is inclined to burn down the big tent the Republican Party has been trying to build, in the event that he loses his bid to stamp his own name on it, running as an independent would not be a simple task for Trump to pull off.
His most immediate problem would be ballot access. Each state has its own requirements for collecting enough valid signatures to get a third-party candidate on the ballot, but the process is both labor- and money-intensive everywhere.
A draft effort in 1992 helped Ross Perot get on the ballot in all 50 states , and he finished with almost 19 percent of the vote nationally -- but no third-party presidential candidate has earned anywhere close to that level of support in the quarter-century since.
And if Trump were to hang on to his hopes of winning the Republican nomination for the time being, only to come up short once the voting begins early next year, he wouldn't have any time to catch his breath before launching an independent run.
Recent history demonstrates the potential pitfalls.
Well in advance of the 2012 presidential campaign, a group called Americans Elect devoted $15 million of an overall budget of more than twice that amount to try to get a “nonpartisan presidential ticket” on the ballot nationwide.
Americans Elect did manage to gain ballot access for a to-be-determined presidential ticket in a majority of states, but the project fizzled out amid myriad problems, controversies and general lack of interest from recruited candidates and the voting public.
“Even for somebody like Donald Trump, there has to be a platform,” said Cara McCormick, who served on Americans Elect’s board of advisers. “Otherwise, he has to create it himself, and that does come at considerable expense.”
As a self-funding billionaire, however, Trump might not necessarily be concerned with this particular financial barrier, which typically prevents third-party White House bids from getting off the ground.
In an interview with The Huffington Post last month, he did not rule out the possibility of spending up to $1 billion on his own campaign.
“I’ll do what I have to do,” he said.
But even if he is worth somewhere in the ballpark of the $10 billion he purports to be (a dubious claim to begin with), spending one-tenth of his fortune on an ego trip doomed to fail would be a big leap, even for someone who thinks as highly of himself as Trump does.
Trump’s second-tallest hurdle for third-party contention is entry into the general election debates.
The Commission on Presidential Debates -- which is co-chaired by a Democrat and a Republican -- has established simple criteria for candidates to appear in the three debates that are typically scheduled during the fall before a general election.
According to the rules the CPD has maintained over the last four presidential races, in order for a third-party candidate to be invited to the debates, he or she must have gained ballot access in enough states to win the required 270 electoral votes and also have earned an average of 15 percent support, according to an average of five national polls.
Jim Glassman, a former undersecretary of state who served in George W. Bush’s administration, is now working for a group called Level The Playing Field that is focusing on getting an independent candidate into the general election debates, as part of the latest effort to break “the two-party stranglehold.”
And in spite of his financial advantages, Glassman does not see Trump as the person to do that.
“It’s not very easy to run successfully as an independent -- very, very difficult,” Glassman said. “I think Donald Trump would be foolish and crazy to run as an independent at this point.”
Still, other people’s opinions of his sanity are unlikely to be determinative factors in the decision-making of a man who spent months vowing that he would prove that the President Barack Obama is not really an American.
Trump previously flirted with a third-party run under the Reform Party banner during the 2000 presidential campaign. He passed on that particular endeavor, even though the Reform Party had qualified to receive money from the federal government to support the run.
Have circumstances changed in a way that would convince him to make a different decision this time around?
According to a New York Times report, former top aide Roger Stone had urged Trump to “minimize his rumination” about a possible third-party run, as long as he remains a viable contender for the 2016 GOP nomination.
Stone and Trump parted ways under contentious circumstances over the weekend.