President Donald Trump’s two eldest sons pushed a false conspiracy theory on Wednesday suggesting that President Donald Trump lost Arizona because his supporters used Sharpie pens to fill out their ballots.

The idea was shared on Twitter by American Conservative Union Chair Matt Schlapp.

“Apparently the use of sharpie pens in gop precincts is causing ballots to be invalidated,” Schlapp wrote on Twitter. “Could be huge numbers of mostly Trump supporters. More to come.”

In a subsequent tweet with the hashtag “Sharpiegate,” Schlapp claimed that he had been contacted by three Trump supporters who used Sharpie pens.

“3 more Trump supporters just contacted me who voted in AZ w sharpies and now are getting stonewalled as they try to verify they are in Trump’s tally,” he tweeted.

But Pima County election officials in Arizona clarified that the claim was “false.” The claim was also rated as “false” by Politifact.

“The felt-tip pen ballot controversy burning through social media is false,” Pima County said in a statement. “Don’t get caught up in it. Arizona ballot tabulating machines can read ballots marked with a felt tip pen. Felt pens are discouraged because the ink can bleed through.”