Joe Biden refers to Donald Trump as a “sick fuck” behind closed doors to his longtime friends and close aides, Politico reported Thursday, citing three people who claim to have personally heard the insult. Another unnamed source reportedly said they’d heard Biden say of Trump: “What a fucking asshole the guy is.” Biden’s disdain for his predecessor has been widely documented, and he appeared to nearly lets his not-so-polite thoughts about Trump sneak out as he gave remarks in Pennsylvania last month. “At his rally, he jokes about an intruder, whipped up by the Big Trump Lie, taking a hammer to Paul Pelosi’s skull,” Biden said in that speech.“And he thinks that’s funny. He laughed about it. What a sick …” Biden didn’t finish the remark, but the attending crowd cheered and chuckled as the president made clear what he wanted to say. Politico reported that the White House declined to comment Thursday on the president’s alleged potty mouth.