And he is not the only beleaguered candidate, in his mind. In 2012, after then-Republican presidential nominee Mitt Romney lost his election bid, Trump tweeted: “This election is a total sham and a travesty. We are not a democracy!”
The Republican National Committee declined to answer whether they agree with Trump that this election could be “rigged" and that 2012 was also “rigged.” Members of Romney’s 2012 legal team, including attorneys Ben Ginsberg, Katie Biber, and Lee Rudofsky, did not immediately respond to ABC News’ requests for comment.
But numerous election experts told ABC News that although the system is imperfect, it is not fundamentally corrupt or rigged against one party.
General elections are primarily run at the state level. In 40 states, elections are overseen by a secretary of state or lieutenant governor. Of those 40 states, 25 of them are Republican and 15 are Democrats, according to Election Line, a nonpartisan, non-advocacy clearinghouse of election information.
“In 20 years covering elections, I have not seen anything less than the highest level of professionalism by election officials across the country,” said David Becker, election expert for the Pew Charitable Trusts. “The voters can feel secure that the results they see on election night represent the true will of the people.”
Daniel Tokaji, a professor at the Moritz College of Law, Ohio State University, said he's "not quite sure exactly what Mr. Trump had in mind with this statement.
"But whatever he meant, there is no realistic possibility of the 2016 general election being “rigged,” he said. “Voter fraud is extremely uncommon, nowhere near the scale that would change the result of a presidential election in any realistic scenario.”
Tokaji added that there have been many improvements in the way we vote — especially in voting technology — that have increased reliability.
David Norcross, who was Chairman of the Republican National Lawyers Association in 2012, said he does not “believe there is any evidence that the 2012 election was stolen.”
But, he said, “that is not to say that our elections are without fraud or that fraud could not impact the outcome of an election."
"Republicans have for years strongly advocated for voter identification because Democrat city machines have historically played fast and loose with turnout often ignoring proper registration or identification,” he said.
True the Vote, an advocacy group that fights voter fraud, did not present evidence of widespread voter fraud, but pointed to examples of troubling election irregularities, like 59 districts in Philadelphia where reportedly Romney got zero votes.
"Mr. Trump is correct that voters need to keep an eye on their elections this November,” said the group’s founder Catherine Engelbrecht.