TORONTO -- U.S. President Donald Trump has claimed that the results of this year's election may be rigged for a number of reasons such as mail-in ballots and their "tremendous" potential for fraud, and has declined to commit to a peaceful transfer of power if he loses.

Matthew Lebo, a political science professor at Western University in London, Ont., told CTV's Your Morning that multiple scenarios could unfold after election night, regardless of who wins.

"If it's really clear that Joe Biden won the election, then it would be really difficult for Donald Trump to hang on to power [and] get inaugurated again in January," Lebo said in an interview on Thursday.

"What's far more likely is it will just be two sides arguing about who won, that Donald Trump might claim victory and then it might be for the courts and for Congress to settle exactly who won."

Speaking to reporters in late September, Trump declined to commit to a peaceful transfer should he lose to Democratic candidate and former vice-president Joe Biden on Nov. 3.

"Well, we're going to have to see what happens," Trump said. "You know that I've been complaining about the ballots, the ballots are a disaster."

"There won’t be a transfer, frankly," he said. "There'll be a continuation."

Trump has repeatedly claimed that the use of mail-in ballots will result in a "rigged election," however, Lebo says the practise is safe despite some states reporting problems with ballot-marking devices.

"The extent of mail-in voting this year is just unprecedented, but there's been lots of states that have been using mail-in voting for all of their elections. Oregon has used nothing but mail-in ballots for years," Lebo said.

"It's a little more complicated, but those complications really could be overcome [and] it can be done safely and tabulated fairly."

He added that there have been "very, very few" cases of voter fraud linked to mail-in ballots. He said there have only been about 30 cases of illegally cast mail-in ballots out of billions cast in the last two decades.

Roughly 15 million Americans have already voted in the 2020 U.S. election either by mail or waiting in long lines for hours to cast early ballots at advance polling stations.

Lebo explained that America may be headed into uncharted territory, given how many people are casting their ballots by mail due to the ongoing COVID-19 pandemic. Because of the time it could take to count those ballots, he said a clear picture of the results might not emerge on election night.

"Different states have different schedules and for some states all the ballots will be counted by election night, but some, you could put your ballot in the mail on election day, and it may not be counted for several days," Lebo said.

"So it might be the case that on election night a state has a certain result, but that's changing day-by-day," he added.

If Trump is ahead on election night, Lebo said he may declare a victory despite some votes having yet to be counted.

"Over the next few days if that lead were too narrow or for [Trump] to lose that lead, you can expect that he would be screaming that he was being cheated out of that particular state, and then he might be in the courts fighting to stop the counting as his lead dwindled past election day," he said.

Lebo said Trump has been hinting at a non- peaceful transfer of power for the past four years.

Despite winning the election and becoming president in 2016, Trump still says that he was "cheated" out of winning the popular vote.

While Trump has not said he would commit to a peaceful transfer of power, Congressional leaders from both parties, including Senate Majority Leader Mitch McConnell and House Speaker Nancy Pelosi, have said otherwise.

"The winner of the November 3rd election will be inaugurated on January 20th," McConnell wrote in a tweet. "There will be an orderly transition just as there has been every four years since 1792."

Democrat Pelosi said at a news conference in September it was "very sad" that the president was even raising the question.

She reminded Trump that the U.S. is not North Korea, Russia, Saudi Arabia or other countries with strongman leaders he openly admires.

"You are in the United States of America. It is a democracy," Pelosi said. "So why don't you just try for a moment to honour our oath of office to the Constitution of the United States."

Pelosi added that she has confidence in American voters to cast their votes and choose the president.

Despite this, Trump has threatened to delay this year's election because of his uncertainty around mail-in voting -- a power a sitting U.S. president does not have.

However, at her confirmation hearings this week, U.S. Supreme Court nominee Amy Coney Barrett refused to say whether she believes Trump has the power to move an election date with an executive order.

Barrett maintained that she would need to hear arguments from both sides on the matter before making a decision.

Moving the election would require the cooperation of Congress, as the general election date is set by an 1845 federal law.

A change to that law would need to be approved by both the Republican-controlled Senate and the Democrat-controlled House, thus Lebo says the election is "pretty set in stone" and likely to go ahead without any delay.

"That's just one of hundreds of answers that [Amy Coney Barrett] did not want to give, but the election I think will occur on time. It’s already occurring now … millions of people have already voted, that voting should end on election day," Lebo said.