On the homestretch of the US presidential election campaign Donald Trump went back to his old Republican primary playbook.

In the race for the Republican nomination he had not just repeatedly complained about being treated unfairly by the GOP and the media, he also had threatened to not accept that outcome and to mount an independent bid.

In last week's third and final presidential debate Trump took his approach of questioning the democratic process to a whole new level when he suggested that he may not accept the outcome of the presidential election contest between him and his Democratic rival Hillary Clinton.

Improper statement

While Trump used the same vocabulary of a "rigged system" he employed in the primary, the public backlash against his remarks was far greater. Even leading Republicans were outraged that their candidate seemed to question the democratic process even before any ballots had been counted, and they urged him to accept the outcome of polls.

"It was improper to say what he said and the way that he said it, given the role of a candidate in a democracy for the office that he is seeking," said Edward Foley, director of the election law program at Ohio State University.

But while Trump's remark was widely viewed as another low point which might further alienate voters' interest in an already toxic presidential campaign, it will likely have little practical consequence.     

No recourse

"This has no meaning whatsoever," said Benjamin Ginsberg, a political science professor at Johns Hopkins University. "It's simply a statement of sour grapes. I think he said it without thinking it through. If at the end of the day he says, 'I don't accept the result of the election,' so what?"

Trump's questioning of the election outcome may have made some sense in the Republican primary, noted Ginsberg, as he could threaten to act as a spoiler by deciding to run as an independent or by urging his voters to not support any nominee other than himself. But in the presidential race, it's an empty threat, he quipped. "What's Trump's recourse - he'll cry?

That's because to challenge the national election outcome on a whole, as Trump seemed to suggest, is practically impossible as the election is carried out and tallied on a state level. As a consequence election results can only be challenged in an individual state if the results are close. But even that step is usually not necessary, explains election law scholar Foley.

Lack of knowledge

"Most states have what they call automatic or mandatory recounts that get triggered by close margins." The trigger for an automatic recount is usually a margin of 0.5 percentage points and doesn't require any action on the part of the candidates.

"I do think the words that he has used suggest some lack of knowledge of the mechanics of the process and how the system works," said Foley.

Because for Trump's remark of not accepting the election outcome to have any real significance, the Republican presidential candidate would need to finish the race at least within striking distance of the 270 electoral college votes needed to win the White House. Only if victory hinges on one or two states where Clinton and Trump are head-to-head is there even a case for legal recourse, said the experts.    

"It's vanishingly rare how often this happens," said Foley. While the 2000 presidential election recount battle in the decisive state of Florida between Al Gore and George W. Bush is often mentioned, it's important to remember that this was an outlier and not the rule.

Best legal minds

"If you go back to 1876, there were three states that were in play and that were outcome determinative," said Foley. In the 1884 and 1916 presidential elections New York and California were tipping states and in each case it took two weeks to determine the winner, noted Foley.  

But at least for now most election polls have Clinton winning comfortably enough to mute any reasonable discussion about legal action. Should that change between now and Election Day, noted Foley, Trump and Clinton have hired the best hands to fight over any possible election disputes. "Were there to be litigation over the election, both sides would have high powered legal talent that they could bring to bear on this."