Who senators choose, and whether Trump ultimately endorses a candidate in the final hours, could set the tone for Trump’s attempts to assert control over the legislative branch.

U.S. Senate Republicans will gather behind closed doors on Wednesday to pick their next leader in the face of a public pressure campaign by supporters of President-elect Donald Trump who favor the long-shot bid of a hardline Trump loyalist.

Sen. John Thune of South Dakota is the new majority leader. He'll replace longtime GOP leader Mitch McConnell, who is stepping aside from the job after nearly two decades.