WASHINGTON — Gov. Jim Justice of West Virginia, a Democrat who was elected last year even as President Trump carried the state by 42 points, is expected to announce Thursday night at a rally with Mr. Trump that he is changing parties, according to three sources familiar with the plans.
Speaking to reporters in the White House Thursday, Mr. Trump promised “a very big announcement” at a gathering in Huntington, W.V., that is expected to draw thousands of supporters from across Appalachia, a region that gave Mr. Trump some of the largest margins of his election.
Mr. Justice, a billionaire coal and real estate magnate, ran as a conservative Democrat and declined to endorse Hillary Clinton in 2016. But even as West Virginia has become a reliable Republican state in presidential elections and further down the ballot, a handful of Democrats have still been able to win office.
Mr. Justice, though, is said to have friendly relationships with some members of Mr. Trump’s family. And before entering politics he gave money to officeholders in both parties while variously registering as a Republican, Democrat, and independent.
Mr. Justice’s decision to change parties will further isolate Senator Joe Manchin, a West Virginia Democrat and himself a former governor. Mr. Manchin has resisted the entreaties of Republicans to change parties and add to the two-seat Senate majority. Some Trump administration officials, eyeing Mr. Manchin’s seat, also had hoped to put him in the cabinet, but he has declined all overtures. Now he must stand for re-election in 2018 without the help of a friendly governor.
Senator Chuck Schumer of New York, the Democratic leader, has paid close attention to Mr. Manchin since the election last year, offering him plum committee assignments.