Donald Trump must be defeated at all costs this November, Bernie Sanders says.

The independent senator from Vermont described the reality TV personality as the “most dangerous presidential candidate in the modern history of this country.”

“This guy is running his entire campaign based on bigotry,” Sanders continued. “Based on trying to divide us up, based on trying to insult Mexicans, Latinos and Muslims and women and African Americans.”

Sanders reminded the audience that Trump was a leader of the “birther” movement, “which tried to delegitimize the first African American president we have ever had.” “This is a guy who must be defeated,” he added.

Over the issue of whether he’d be able to work with Hillary Clinton, who beat him in the race to become the Democratic party’s presidential nominee, Sanders admitted it was “no secret” they’d had disagreements.

“But what I intend to do, the day after Hillary Clinton is elected president of the United States, is to do everything I can to make sure she goes forward as progressively as she can,” he said.

Check Sanders’ comments out in the clip above.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.