Sen. Bernie Sanders, I-VT., said in a debate with Ohio Gov. John Kasich on CNN Tuesday night that it was clear after the president shared classified information with Russian officials earlier this week that he doesn't know how to serve as president.

"I think for whatever reason Donald Trump doesn't fully understand what being president of the United States is about."

The comments came in response to an audience member question.

"Speaker Paul Ryan has been on record saying anyone who jeopardizes national security and classified information should have their security clearance removed immediately. Should the same standard apply to the president as well?" Gina Walkington from Wisconsin asked.

Sanders responded by saying President Trump endangered national security when he shared classified intelligence with Russian officials last week. The senator also noted that the president excluded all American media during the meeting.

"This is a big deal and this president had better learn what it's like to be president and not share classified information with people who do not wish us well," Sanders said.