W ASHINGTON—Centrist Sen. Thom Tillis (R., N.C.) said he won’t seek re-election in 2026, less than 24 hours after he voted against a motion to advance President Trump’s tax and spending megabill, drawing public backlash from the president.

A popular former Democratic governor, Roy Cooper, is expected to announce a bid this summer. The Republicans are banking on an endorsement by President Trump to clear their field.

WASHINGTON — Republican Sen. Thom Tillis of North Carolina said Sunday he will not seek reelection next year, an abrupt announcement that came one day after he staked out his opposition to President Donald Trump’s tax breaks and spending cuts package because of its reductions to health care programs.