Republican presidential nominee Donald Trump, at a town hall meeting Aug. 1 in Columbus, Ohio, suggested that the upcoming presidential election will be “rigged.”

“I'm afraid the election is going to be rigged, I have to be honest,” Trump said, without providing further evidence or explanation.

In ABC’s popular television show “Scandal,” fictional Republican presidential candidate Fitzgerald Grant wins a crucial district in a swing state after campaign operatives hack local voting machines. The votes are just enough to turn the tide and secure the presidency for Grant.

Kerry Washington portrays Olivia Pope in ABC's ''Scandal''

“That’s fiction,” noted Richard Hasen, an election law expert and professor of law and political science at the University of California, Irvine. In reality, there have been small, local problems with fraud, but never on the scale that would throw a state’s Electoral College votes, Hasen told Bloomberg BNA.

Trump has expressed concerns about people voting multiple times to support his position on voter ID, Hasen suggested. “That fits in with a type of claim that we’ve heard some conservatives make over the years that voter fraud is rampant and is causing Democrats to win elections,” he said.

But in fact, the evidence shows that “impersonation fraud,” where someone goes to the polls and pretends to be someone else, is extremely rare, Hasen said.

“That’s not to say there’s no fraud,” Hasen said. “There are instances, for example, of absentee ballot fraud where people buy and sell absentee ballots.”

But every state and local jurisdiction has some way of verifying identity and recording votes, which would prevent someone from voting more than once, Hasen said.

Asked about Trump’s concerns at an Aug. 4 press conference, President Barack Obama asked what that even means. “Of course the elections will not be rigged,” he said.

“If Mr. Trump is suggesting that there is a conspiracy theory that is being propagated across the country, including in places like [Republican-controlled] Texas … that's ridiculous,” Obama said. “That doesn't make any sense.”

In a tweeted response, Trump said Obama should ask about the controversy regarding the Democratic National Committee, in which leaked DNC e-mails revealed some top officials allegedly strategizing against the Bernie Sanders campaign in favor of Hillary Clinton’s.

“President Obama should ask the DNC about how they rigged the election against Bernie,” Trump said.