Sarah Sanders rages at ex-aide's 'lack of knowledge' after he suggests Mueller has proof to send Trump to jail

White House Press Secretary Sarah Huckabee Sanders on Monday insisted that President Donald Trump did not collude with Russia to win the election even though a former campaign staffer suggested otherwise.

Former Trump campaign aide Sam Nunberg revealed on Monday that he would not comply with a subpoena from special counsel Robert Mueller's Russia investigation. During an interview with MSNBC, Nunberg also said that he learned in a previous interview that Mueller may already have proof of crimes committed by Trump during the election.

But at Monday's White House press briefing, Sanders slammed Nunburg and insisted that he was lying.

"I definitely think he doesn't know that for sure because he's incorrect," Sanders said. "I've said many times before that there was no collusion with the Trump campaign. Anything further on what his actions are, he didn't work at the White House so I certainly can't speak to him or lack of knowledge that he has."

Watch the video below from CNN.