Rep. Andy Kim (D-N.J.) announced Saturday he would challenge indicted Sen. Bob Menendez, becoming the first major intraparty challenger to emerge since Menendez insisted he would not step down in the face of charges he accepted bribes from three businessmen.

“After calls to resign, Senator Menendez said ‘I am not going anywhere,’” Kim wrote on the social media site formerly known as Twitter. “As a result, I feel compelled to run against him. Not something I expected to do, but NJ deserves better. We cannot jeopardize the Senate or compromise our integrity.”

Following the unsealing of the Justice Department’s indictment of Menendez on Friday, leading New Jersey Democrats, including Gov. Phil Murphy, have called for him to resign from his post. Menendez was previously charged in a different corruption scandal, though the Justice Department dropped the charges after a hung jury led to a mistrial in 2017.

In a statement Friday night, Menendez angrily beat back calls for him to leave office.

“It is not lost on me how quickly some are rushing to judge a Latino and push him out of his seat,” he said. “I am not going anywhere.”

Kim, now in his third term, may not be the only Democrat interested in challenging Menendez, and a resignation would almost certainly lead to a crowded primary in safely Democratic New Jersey. Reps. Mikie Sherrill and Josh Gottheimer could also enter the contest.

Menendez, who has not officially announced he intends to run for reelection, also has two lesser-known challengers from the GOP: consulting firm owner Shirley Maia-Cusick and Christine Serrano Glassner, the mayor of suburban Mendham Borough.