As Donald Trump amps up his allegations that the election will somehow be rigged against him, he and his surrogates have latched on to a myth that fraudulent votes somehow swung North Carolina to President Obama’s favor in 2008.

Trump himself referenced the theory — that was first put forward in a flimsy and controversial 2014 Washington Post op-ed — from the stump in a speech in Wisconsin Monday evening, where he told the crowd, “It is possible that non-citizen votes were responsible for Obama’s 2008 victory in North Carolina.”

He went into more specifics at campaign rally in Colorado Tuesday.

“In 2014 the Washington Post, another beauty, published an article entitled ‘Could Non-Citizens Decide the November Election.'” Trump said. “The article found that 14% of non-citizens were registered to vote, 14% were registered to vote. And we’re not supposed to talk about it. And your Republican leaders said ‘everything is peachy dory’ right?”

The article Trump referenced was actually a controversial op-ed published by the Washington Post blog Monkey Cage. Its authors’ mention of North Carolina was almost purely speculative, and based not on any reports from the election itself, but rather data they had crunched regarding the voter registration rates of non-citizens. Their logic was rebutted by three separate pieces on the Washington Post site alone, and their findings questioned by a peer-reviewed article.

But that hasn’t stop Trump and his surrogates from fanning the myth that some how undocumented immigrants were able to hand Obama North Carolina in 2008.

Sam Clovis, Trump’s campaign co-chair, defended the GOP nominee’s claim on local Boston radio Tuesday morning.

“I’ve done a lot of work and study in this area, so here’s what happens: you have the opportunity for illegal immigrants to come to the state, and the state loosens its laws to provide for individuals to get drivers licenses in the state, illegal or otherwise,” Clovis said, not mentioning that North Carolina doesn’t even allow undocumented immigrants to obtain driver’s licenses, as ThinkProgress pointed out.

Clovis went on to float, without evidence, that undocumented immigrants were then able to used these alleged licenses to register to vote.

“This is why we seem to have this type of phenomenon going on across a lot of states,” he said.

Trump senior advisor Boris Epshteyn reiterated a version of the claim on CNN Tuesday afternoon.

“Barack Obama may have won in 2008 in North Carolina due to illegal voting,” he said, getting pushback from Jake Tapper, who asked for proof the the assertion.

“The Washington Post story that just came out a few days ago,” Epshteyn said. “Take a look at the Washington Post story that is saying that about five percent of voting in North Carolina may have been by people who are non-citizens who should not have been voting and swung North Carolina to Mr. Obama, to President Obama because of how tight that race in North Carolina was in 2008.”