Mega-pop star John Legend has scolded supporters of presidential hopeful Bernie Sanders for their “nastiness,” saying their attacks on fellow candidate Elizabeth Warren reflect poorly on the Vermont senator.

Legend threw his weight behind Sen. Warren (D-MA) on Tuesday, saying that he will be voting for Warren in the upcoming California Democratic primary. But he also said that he will vote for Sen. Sanders (I-VT) if he manages to clinch the Democratic nomination.

The singer warned Sanders supporters in a tweet Wednesday that they could be driving people away with their behavior, advising them to just “chill.”

Sens. Sanders and Warren have been feuding since CNN ran a story earlier this week claiming that Sanders once said that a woman couldn’t win the presidency. The article only cited anonymous sources, leading some to speculate that Warren’s camp leaked the information in an effort to damage her political opponent.

Warren herself backed up the allegation to CNN on Monday, saying in part in a statement, “I thought a woman could win; he disagreed.”

Sanders has denied making the comment, telling the network that the claim is “ludicrous.”

The quarrel only got uglier on Tuesday during the Democratic presidential debate. Warren appeared to reject Sanders’ offer to shake hands at one point during the televised event.

During the debate, Sanders supporters launched the Twitter hashtags #NeverWarren, #LyinLiz, and #WarrenIsaSnake, while also tweeting the snake emoji when referencing Warren.

CNN further enraged Bernie bros during Tuesday’s debate when moderator Abby Phillip addressed the feud, asking Sanders, “Why did you say that?”

Sanders replied, “Well, as a matter of fact, I didn’t say it.”

The moderator then asked Warren, “What did you think when Sen. Sanders told you a woman could not win the election?”

The exchange led the Twitter hashtag #CNNisTrash to start trending.

Legend initially endorsed Warren back in October, telling Vanity Fair that the Massachusetts senator represents the “best candidate running today.” Warren responded by telling Legend that she is “grateful down to my toes for your support.”

The pop star has been a vehement critic of President Donald Trump, recently describing the commander in chief as a “cancer” who “needs to be removed from office,” in a tweet posted in November.

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