Senators Elizabeth Warren and Amy Klobuchar immediately went after Mike Bloomberg during his first appearance in a Democratic debate on Wednesday night, calling out his treatment of women.

"I'd like to talk about who we're running against," Warren said. "A billionaire who calls women fat broads and horse faced lesbians, and no, I'm not talking about Donald Trump, I'm talking about Mayor Bloomberg.

"Democrats are not going to win if we have a nominee who has a history of hiding his tax returns, of harassing women," she added.

Warren also called out Bloomberg for his support of policies that hurt people of color while he was mayor of New York City.

"And of supporting racist policies like red lining and stop and frisk. Look, I'll support whoever the Democratic nominee is, but understand this. Democrats take a huge risk if we just substitute one arrogant billionaire for another," Warren said.

The Las Vegas debate was the first debate Bloomberg qualified for. Before Bloomberg had taken to the stage, multiple candidates had spoken publicly about their interest in debating the billionaire.