Sen. Bernie Sanders called President Trump a "fraud" on Thursday, and said he is proposing some of the most destructive policies the U.S. has ever seen in generations.

"They're incredibly worried about the temperament of this president," the Vermont independent said on MSNBC when asked about how people are reacting to Trump's first six months.

"But we should not also ignore ... it's not just his temperament, it's not just his stupid tweets," he said. "Do not forget for a second that the policies that he is proposing are the most destructive policies being proposed in our lifetimes."

Sanders said he hopes Congress defeats the GOP effort to dismantle Obamacare, and said voters need to see that Trump is not working in the interests of rural voters.

"I hope that Trump supporters in rural states understand that when he told them during the campaign that he was gonna stand up for working-class people was nothing but a lie," he said.

"He has got to be exposed for the fraud that he is, not just focusing on his temperament and on his tweets, but on his extremely right-wing policy that is paid for by the Koch brothers and other billionaires," he said.