Is the election really 'rigged,' as Trump and Sanders say?

"I'm telling you, Nov. 8, we'd better be careful, because that election is going to be rigged," Donald Trump told Fox News this summer.

Earlier, Bernie Sanders supporters claimed the Democratic National Committee was biased towards Hillary Clinton — claims that gained credibility with the leak of DNC emails and the departure of DNC chairperson Debbie Wasserman Schultz.

But what does calling an election "rigged" really mean? What does it signal to voters?

"We don't have one national electoral system, we have fifty states and then those states delegate that to counties" said Robert Smith, professor of political science at San Francisco State University during a conversation with MPR News host Kerri Miller. "And so there are inefficiencies and there are possibilities of corruption - not in the rigged sense."

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While Smith and other election experts agree that the risk is not nonexistent — with one study finding 31 instances of voter fraud in the U.S. from 2000 to 2014 — when Trump speaks of a "rigged election" he might be overshooting the actual problems with the system.

Smith pointed to long lines, outdated voting machines and voter ID laws in certain states as having a larger effect on the election than any amount of voter fraud because these are things that discourage, or even prevent people from voting.

During the same conversation former Mitt Romney strategist Stuart Stevens pointed to an example of potential voter fraud in the form of leaked emails that appeared to show Democratic Party members trying to undercut Bernie Sanders before the 2016 primary elections. Stevens says this is a fair reason to worry about the integrity of our electoral system.

"But that doesn't mean there is some giant conspiracy to rig it," said Stevens. "This is bad spy thriller stuff and what it does is, it damages those who are serious people trying to address serious problems."

Other Republicans have agreed on this point, saying focusing on voter fraud is detracting from other, more pertinent issues in the election. Even so, associate professor of political science at the University of Miami, Joseph Uscinski, says the fear and doubt is likely to persist, at least until after the election.

"When we do polls prior to elections you have about two-thirds of the country who think that there's going to be some kind of malfeasance in the election," Uscinski said. "After the results are announced then that number cuts in half because the winning party believes there was no fraud and only the losing party thinks there was fraud."

Uscinski says that the type of fraud people are most concerned about also depends on party allegiances — with Democrats more concerned with regulations that prevent their voters from voting, and Republicans worrying that opponents will be able to vote multiple times.

Professor Robert Smith suggests that while someone voting in your place is not anything to worry about, there is somewhere else voters might point their anger and uncertainty:

"Gerrymandering is a deliberate rigging of the voting representation process," said Smith, referring to the act of manipulating electoral boundaries to make a more favorable environment for a certain political parties or classes of people.

He added that Americans with the most money still have the most influence over politics, with Wall Street flaunting a great deal of influence over Congress via special interest groups.

"Trump is talking about a particular aspect of rigging an election outcome that is not a part of the American political system, never has been," said Smith. "But that is not to say that other parts of the system, economic and political, are not, quote, rigged."