ROBERT SIEGEL, HOST:
Donald Trump is down in the polls. He has faced wave after wave of negative stories. And on the campaign trail and on Twitter, he is hitting one point over and over.
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DONALD TRUMP: It looks to me like a rigged election.
SIEGEL: Trump has produced no evidence of fraudulent voting. But this idea that the election is rigged against him is something that he's talked about before. NPR's Scott Detrow explains.
SCOTT DETROW, BYLINE: Mostly Trump's rigged talk has focused on the media. As new allegations of sexual assault keep emerging, Trump says the media is aligned with Hillary Clinton. For Trump, this includes everyone from The New York Times to "Saturday Night Live."
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TRUMP: The election is being rigged by corrupt media pushing completely false allegations and outright lies in an effort to elect her president.
DETROW: But Trump is also talking and tweeting about how the election is rigged at the polls and voicing concerns about voter fraud. That worries people like Edward Foley, the head of Ohio State University's election law program. Foley has written about disputed elections and he says they look far different than the broad conspiracy Trump has been mapping out.
EDWARD FOLEY: For us to be even remotely realistic about thinking about the risk of a rigged presidential election, it would have to be the context in which the presidential election came down to one or a few states and those states were also extremely close in their votes.
DETROW: That's not what the polls look like right now. Trump has talked about rigged races before but only at times he was losing, like in April after Ted Cruz outmaneuvered him in the hunt for delegates at state conventions in places like Colorado.
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TRUMP: Our Republican system is absolutely rigged. It's a phony deal.
DETROW: In fact, Cruz had aggressively organized in those states, while Trump had largely ignored the important role state conventions play in assigning primary delegates. Trump also talked about a rigged election when he trailed Clinton in the polls in August. As the race tightened, that talk disappeared. Now it's back. And it raises the concern that if Trump loses, he won't concede.
Foley says that has never happened in high-profile presidential races. He says a norm developed in the early days of American elections.
FOLEY: That even if you think there were some irregularities, you know, for the sake of the system as a whole, accept defeat, move on and then win fair and square the next time.
DETROW: Foley says he believes the American democratic system is strong and that other institutions like Congress can help legitimize and validate an election if the loser won't. He points to statements like what Trump's running mate Mike Pence told "Meet The Press's" Chuck Todd this weekend.
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CHUCK TODD: Will you accept the results of the election?
MIKE PENCE: We will absolutely accept the results of the election. Look, the American people will speak in an election that'll culminate on November 8.
DETROW: But since then, Pence has sounded a bit more like Trump. Today he told an Ohio crowd the national media is trying to rig the election. Scott Detrow, NPR News. Transcript provided by NPR, Copyright NPR.