Elizabeth Warren has launched a scathing attack on billionaire Michael Bloomberg, slamming him over past sexist comments and likening him to Donald Trump.

As the 78-year-old former New York mayor made his first appearance in a Democratic debate, he came under fire from his rivals in quick succession.

“I’d like to talk about who we are running against. A billionaire who calls women fat broads and horse faced lesbians. And no I am not talking about Donald Trump. I am talking about Mayor Bloomberg,” said Ms Warren.

“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.”

The comments were delivered as a series of polls showed Mr Bloomberg had soared after spending around $400m of his own money on political advertising.

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An average collated by RealClearPolitics put Mr Bloomberg on 16 points nationally, behind Bernie Sanders and Joe Biden, but ahead of Ms Warren, Amy Klobuchar and Pete Buttigieg.

In his first response on Wednesday night in Las Vegas, just days ahead of the Nevada caucus, Mr Bloomberg claimed that Mr Sanders, the frontrunner, could not defeat Donald Trump if he was the party’s candidate.

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“I don’t think there’s any chance of the senator beating President Trump,” Mr Bloomberg said.

“If he goes and is the candidate, we will have Donald Trump for another four years, and we can’t stand that.”

In particular, he claimed Mr Sanders healthcare plan – so-called Medicare for All – would hurt his chances.

“You don’t start out by saying I’ve got 160m people I’m going to take away the insurance plan that they love,” he said. “That’s just not a ways that you go and start building the coalition that the Sander’s camp.”

Ms Warren and others on the stage also called on Mr Bloomberg to release several women who alleged sexism and misogynistic behavior from non-disclosure agreements they had signed at his company.

Asked about sexually suggestive comments he had made in the 1990s, and allegations he operated a hostile workplace, he said his firm was now ranked as a good place for women to work.

Ms Warren said: “I hope you heard what his defence was. I’ve been nice to some women. That just doesn’t cut it.”

She asked Mr Bloomberg why he would not release the women from the non-disclosure agreements.