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.

As Senate Republicans prepare to vote Wednesday on a new majority leader, Trump is already weighing in with demands for recess appointments.

With very few votes left to count in last week’s election, the Republican Party appears to have flipped four Senate seats—in Pennsylvania, Ohio, West Virginia, and Montana—giving it a presumptive 53–47 majority.

Political control of the Arizona Senate was on the ballot Tuesday. Six days of counting show Republicans likely to not only retain control of the 30-member chamber, but to possibly gain a seat . The Senate is currently split 16-14.