On the heels of the general election last week, there’s another important vote on tap this Wednesday in Washington that will greatly impact what President-elect Donald Trump can accomplish during his four years in office: Republicans in the Senate will vote by secret ballot to choose a new leader.

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.

Senate Republicans returned to Washington for the first time since they secured the Senate majority to determine who will be the new party leader in the chamber.

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.