Sen. Bernie Sanders's (I., Vt.) campaign chair criticized rival Pete Buttigieg Friday, accusing him of being bought by special interests and "adopted" by the billionaire class.

"[Buttigieg] is not a billionaire himself, but the billionaire class has adopted him as one of their own. He has cozied up to the billionaire class," Faiz Shakir said on MSNBC. "You have to ask, ‘Why does the billionaire class feel so comfortable with Pete Buttigieg?' And the answer is that they're able to influence some of the policies.

"This is a candidate in Pete Buttigieg who used to be for Medicare for All, proudly proclaimed his desire to be for Medicare for All. Suddenly while he's campaigning for president, he accepts money from Aetna, from Pfizer, from a bunch of health insurance companies, from a bunch of drug companies. And then he backs off of Medicare for All."

MSNBC anchor Katy Tur asked Shakir if he was equating Buttigieg with special interest groups.

"For sure. He has accepted money from special interests, he has a super PAC supporting him. He has gone into wine caves and solicited money from the highest billionaires and millionaires in this country," Shakir responded. "He has gotten corporate executives behind his campaign, accepted them from fossil fuel financiers, accepted them from pharmaceutical from, health care—you name it, he's accepted their money in order to fund a campaign that has then cozied up with those individuals to make policies that benefit them."

Before Shakir's appearance, Sanders tweeted an attack against Buttigieg for taking money from billionaires.

This election is fundamentally about whose side you are on. #PetesBillionaires pic.twitter.com/hZi3uzCmvJ — Bernie Sanders (@BernieSanders) February 7, 2020

Buttigieg holds a narrow lead over Sanders in the Iowa caucus at the time of this writing, although the results remain in doubt. The pair will take the stage along with five other Democratic presidential candidates Friday night for a debate in New Hampshire.