>>4399699 (lb)Thanks anon. 26 D seats need to be sworn in on the 1st day of 116th Congress 7 R seats. That means 21 D senators are returning without need to be sworn in and 46 R seats don't need to be sworn in. Makes a Senate of 67 at the close of 115th. It takes 45 to equal 2/3. It takes 2/3rd vote to expel a member. At the close of 115th Congress, R will have 2/3 for a very short window. They could expel the D's returning if they had sufficient evidence of fraud or crimes. EX: Feinstein. Her term ends at noon 1/3/19 and she needs to be sworn in to serve on the 116th. The end of term is constitutional and must happen. The beginning of 116 start time is up to the last efforts taken by the 115. The new Senate begins with 67 members ( some could be arrested over Christmas break thereby decreasing that number) all other seats are considered vacant until everyone is sworn in. The procedure for swearing in is based on norms and follows a chain of events. It is not constitutional. A keystone is the last thing to put into place to hold the entire thing up and the 1st thing to take out when dismantling something.