One of Graham Platner’s biggest supporters is urging him to withdraw his candidacy for senator of Maine.

On Tuesday, Sen. Bernie Sanders (I-Vt.) said he told Democrat Graham Platner to withdraw from the race after a rape allegation against Platner came to light.

“I have spoken with Graham Platner about the best path forward for Maine,” Sanders said. “In light of these very serious allegations, I have recommended that he step aside.”

Sanders, a progressive Senate Democrat, was a big backer of Platner, who joined the race to flip the Senate seat held by Sen. Susan Collins (R-Maine).

Democrats are hoping to retake the Senate majority in November. 

Several of Sanders’ Senate colleagues who had backed Platner, including Sens. Elizabeth Warren(D-Mass.), Chris Van Hollen (D-Md.) and Ruben Gallego (D-Ariz.), have withdrawn their support of Platner.

New York City Mayor Zohran Mamdani has also come out against Platner.