Andy Kim, a three-term congressmember who upended New Jersey’s political landscape in his quest for higher office, was appointed to the U.S. Senate Sunday.

Kim, 42, takes office following the resignation of interim Sen. George Helmy, who had long said he would leave office once the results of the 2024 election were certified. He will fill the seat vacated by Bob Menendez this summer following his federal conviction.

“Today, I am appointing Senator-elect Andy Kim to the United States Senate so he can begin his term in office before the new year begins,” New Jersey Gov. Phil Murphy said in a statement. “Taking this step will allow Senator Kim to embark on the smoothest possible transition into his new role so he can hit the ground running serving the people of New Jersey.”

Kim was elected last month over Republican Curtis Bashaw by just shy of a 10-point margin — a relatively narrow victory for a New Jersey Democrat compared to previous Senate races, but nearly four points above Kamala Harris’ closer-than-expected six point margin over President-elect Donald Trump.

“It’s an honor to get to represent the state that gave my family a chance at the American Dream in the U.S. Senate,” Kim said in a statement. “It’s a dream that remains out of reach for too many of our neighbors, and one that I’m ready on day one to fight for. I want to thank Governor Murphy and Senator Helmy for ensuring that New Jersey was well represented during this transition, and look forward to getting to work for the people.”

A Moorestown resident who lives with his wife and two young children, Kim ran a campaign heavily focused on ethics following the indictment of longtime senator Menendez, who resigned in August following his July conviction on 16 corruption counts.

New Jersey’s Democratic power brokers did not have Kim in mind to replace Menendez, who they had remained supportive of during a previous corruption trial, but who they found politically untenable to support following his stunning September 2023 indictment for trading political favors for gold bars and acting as an unregistered foreign agent.

But Kim — known for his mild manner and a famous photograph of him cleaning the Capitol in the wake of the Jan. 6 riot — eschewed power brokers’ support when he declared his candidacy for Senate just one day after Menendez was indicted. First lady Tammy Murphy, by contrast, ran the more traditional way by courting support of party power brokers who could wield their influence to award her “the line,” which in most counties bestowed favorable ballot placement in the primary.

Kim sued, arguing the line was unconstitutional, and a U.S. District Court judge agreed, tossing the line out for the 2024 Democratic primary and likely for all future primary elections. And Tammy Murphy, who had faced anger on the left for her courting of political bosses, dropped out of the race just before the decision.

Kim ran on expanding abortion rights in the wake of the Supreme Court’s overturning of Roe v. Wade, expanding health care and implementing ethics measures, like a congressional stock trading ban. But his most lasting legacy may be the dramatic change to New Jersey’s ballot structure, with primary ballots now organized by office sought rather than party endorsement.

The change, though seemingly technical, threatens to diminish the influence of New Jersey county chairs that have for decades been able to influence, or in some cases single-handedly decide, which candidates become the primary front-runners.

Now Kim holds one of just three statewide elected offices in New Jersey, and his relationship with Murphy, who will leave office in January 2026, along with some of the state’s Democratic leaders, remains strained.