Bernie Sanders called out Donald Trump last night over the Republican’s recent debate waffling.

On HBO’s “Real Time,” the Democratic presidential hopeful said he “would’ve loved” to have debated the presumptive GOP nominee — and he’s still holding out hope that such a TV event happens.

“If he’s changed his mind four times in two days, change it a fifth time,” Sanders said to Bill Maher.

After a such a change of heart, Trump squashed the possible event yesterday, calling it “inappropriate.” Sanders seems to think the decision was one of pure cowardice, however.

Also Read: Donald Trump Squashes Bernie Sanders Debate, Calls It 'Inappropriate'

“Trump claims to be a real tough guy, pushes people around — hey, Donald come on up, let’s have a debate about the future of America,” the liberal politician challenged the conservative billionaire businessman.

Those wouldn’t be the only harsh words Sanders directed at the Donald during the 11-minute interview.

“This guy is a pathological liar,” Sanders said of the possible next president. “He would be, not only an embarrassment, a real danger to this entire world.”

Watch the full sit-down conversation via the video above.