Billionaire media businessman and former three-term Mayor of New York City Michael Bloomberg entered the Democratic primary on Sunday expressly to attack Sen. Bernie Sanders' attempt to win the party's 2020 nomination, the Sanders campaign charged Monday.

"Bloomberg is primarily motivated by a desire to stop Bernie and his working-class movement," claimed Sanders speechwriter David Sirota Monday in his Bern After Reading newsletter.

According to Sirota, the timing of Bloomberg's announcement lines up with Sanders' rise in the polls and a well-reported meeting between the media mogul and Amazon founder Jeff Bezos, one of the two wealthiest men in the world alongside Microsoft founder Bill Gates. Bloomberg is also close with Disney's Bob Iger, Sirota said.

Bloomberg's run is reminiscent of the billionaire's decision in 2016 to float a run in order to take down the Sanders campaign.

"Bloomberg began floating the idea of a presidential bid in 2016, just as Bernie was beginning to gain momentum in that race," wrote Sirota. "At the time, Bloomberg disparaged Bernie and his campaign’s challenge to Wall Street."

Sanders, in a statement Friday in advance of Bloomberg's entrance in to the race, said he was "disgusted" that Bloomberg believed the race could be bought.

"I'm disgusted by the idea that Michael Bloomberg or any other billionaire thinks they can circumvent the political process and spend tens of millions of dollars to buy our elections," Sanders said.

The Vermont senator doubled down on those criticisms at a rally on Sunday in New Hampshire.

"We do not believe that billionaires have the right to buy elections," said Sanders. "That is why multi-billionaires like Michael Bloomberg are not going to get very far in this election."

On MSNBC Monday, anchor Katy Tur wondered if Bloomberg has another candidate in mind to take down.

"Is this a real campaign, is he really running?" wondered Tur. "Or is he running to torpedo Elizabeth Warren?"

Warren, in New Hampshire on Sunday, said that while she accepts some excesses of wealth she draws the line at billionaires having more political power than the rest of Americans.

"I understand rich people are going to have more shoes than the rest of us," said Warren. "They're going to have more cars than the rest of us, they're going to have more houses—but they don't get a bigger share of democracy. Especially in a Democratic primary."