The political walls are closing in on Sen. Bob Menendez, the New Jersey Democrat under a federal indictment accusing him of corruption-related offenses. New Jersey Sen. Cory Booker’s decision on Tuesday to call for Menendez’s resignation, after days of silence on the matter, was a uniquely damaging political blow to the state’s senior senator, who is now faced with a thinning list of allies in Washington, DC, and his home state, where local leaders are lining up against him. Booker, who said he found the allegations against Menendez “hard to reconcile with the person I know,” instantly became the most prominent Senate Democrat, even among those facing tough reelection races next year, to publicly push for Menendez to step down. By Tuesday evening, more than half of the party’s Senate caucus had called on Menendez to give up his seat. The charges against Menendez, who is up for reelection next year, come at a fraught moment for the narrow Senate Democratic majority, which is facing an uphill battle to keep control of the chamber in 2024. Though New Jersey is a reliably blue state on the national level, Democratic Gov. Phil Murphy won a second term in 2021 by only three points, giving Republicans some reason for optimism – particularly if Menendez is on the ballot while under indictment. Senate Democratic leadership has mostly taken a wait-and-see approach with Menendez, but Michigan’s Gary Peters, the chair of the party’s campaign arm, said on social media late Tuesday afternoon that Menendez was “no longer able to serve effectively” and urged him to resign. In a long and detailed statement, Booker referenced a previous case that Menendez ultimately beat, noting that “Senator Menendez is again facing a federal indictment, one that contains shocking allegations of corruption and specific, disturbing details of wrongdoing. “I believe stepping down is best for those Senator Menendez has spent his life serving,” Booker concluded. Booker broke his silence after similar calls from rank-and-file Senate Democrats, including Tammy Baldwin of Wisconsin, Jon Tester of Montana and Jacky Rosen of Nevada, who all face competitive reelection races next year. “While Senator Menendez enjoys the presumption of innocence until proven guilty and will have his day in court to defend himself, I believe it’s best for his constituents, the American people, and our national security for the Senator to step down,” Baldwin said in a statement Tuesday morning. Tester echoed Baldwin’s concerns, saying in a statement that Menendez “should resign for the sake of the public’s faith in the U.S. Senate.” Rosen called the charges Menendez is facing “a distraction that undermines the bipartisan work we need to do in the Senate for the American people.” Sens. Tammy Duckworth of Illinois, Richard Blumenthal of Connecticut and John Hickenlooper of Colorado joined their colleagues’ appeals later in the day. Pennsylvania Sen. John Fetterman was the first to call for Menendez’s resignation over the weekend. His office has said he will return $5,000 in donations his campaign received from Menendez’s political action committee last cycle. Other senators who have called for Menendez to resign include Sherrod Brown of Ohio and Bob Casey of Pennsylvania, who are both considered vulnerable for reelection next year. Menendez received some tepid support from others, including Sens. Joe Manchin of West Virginia, Tim Kaine of Virginia and Catherine Cortez Masto of Nevada, who all pointed to either the unfolding legal process or suggested that New Jersey voters should have the last word. “It’s up to the people of New Jersey,” New Mexico Sen. Ben Ray Luján said. “They’ll be making a decision in the next few months.” Menendez pushes back Menendez and his wife, Nadine Arslanian Menendez, are accused of accepting “hundreds of thousands of dollars in bribes” in exchange for the senator’s influence. Prosecutors allege the bribes included gold, cash, home mortgage payments, compensation for a “low-or-no-show job” and a luxury vehicle. Menendez on Tuesday would not say whether he would run for reelection. “I’m here to do the work for the people of New Jersey,” he told CNN when asked if he would run again. Asked why he wouldn’t resign, he told reporters: “Because I’m innocent. What’s wrong with you guys?” The senator was defiant against the calls for his resignation in an appearance Monday, accusing those who “rushed to judgment” of doing so for “political expediency.” “I recognize this will be the biggest fight yet,” Menendez said, referencing the legal battle ahead. “But as I have stated throughout this whole process, I firmly believe that when all the facts are presented, not only will I be exonerated, but I still will be New Jersey’s senior senator.” A lawyer for Nadine Arslanian Menendez said she denies any wrongdoing and would fight the federal indictment. The New Jersey senator has served in the chamber since 2006 after 13 years in the US House, where he rose to be the No. 3 Democrat. He previously fought off federal bribery and corruption charges that were brought in 2015. Rep. Andy Kim, who represents New Jersey’s 3rd Congressional District, announced Saturday that he plans to challenge Menendez in the Democratic primary next year should the incumbent run for reelection. Ravi Bhalla, the mayor of Hoboken, New Jersey, outside New York City, is considering a Democratic primary challenge to the senator’s son, first-term Rep. Rob Menendez, who won the deep-blue 8th Congressional District last year with heavy support from the local establishment. The younger Menendez said in a statement over the weekend that he had “unwavering confidence” in his father’s ability to represent New Jersey, despite his federal indictment. This story has been updated with additional information.