Sen. Thom Tillis, R-N.C., walks to the chamber as senators arrive for votes and policy meetings, at the Capitol in Washington. (AP)Republican US Senator Thom Tillis said on Sunday he will not seek reelection next year, a day after President Donald Trump said he would consider supporting challengers to Tillis in response to his vote against the White House’s signature tax-cut bill.Tillis was one of two Republican senators on Saturday to vote against opening debate on Trump’s sweeping tax-cut and spending bill, a procedural step necessary to advance the legislation. His North Carolina seat is seen as one of the few competitive Senate races in the 2026 midterm elections, when control of both chambers of Congress will be at stake.While the Republican-controlled US House of Representatives is considered up for grabs, Democrats face an uphill battle in trying to reclaim a Senate majority. Republicans hold a 53-47 edge, and all but two Republicans up for election – Tillis and Susan Collins in Maine – are in states that Trump carried easily in the 2024 presidential election.Former US Representative Wiley Nickel is the most prominent Democrat who has announced a run against Tillis, but party leaders have been hoping that former Governor Roy Cooper, who remains popular in the state, will jump into the race.In a statement, Tillis made no mention of Trump but bemoaned the political gridlock that has gripped Congress.“In Washington over the last few years, it’s become increasingly evident that leaders who are willing to embrace bipartisanship, compromise, and demonstrate independent thinking are becoming an endangered species,” he said.Following Tillis’ “no” vote on the tax-cut bill on Saturday, Trump attacked him on social media, saying the senator was making a “big mistake” and vowing to meet with potential Republican challengers in the coming weeks.Story continues below this adTillis had voiced several objections to the bill, including concerns over how the proposed legislation’s cuts to the Medicaid healthcare program for lower-income Americans could impact his constituents.Stay updated with the latest - Click here to follow us on InstagramTags:donald trump