The 1886–1887 United States Senate elections were elections that had the Republican Party lose two seats in the United States Senate. At the beginning of the 50th Congress, therefore, Republicans had the slimmest possible majority due to a vacant Democratic seat: 38 out of 75 seats. Once that vacancy was filled, Republicans maintained control as the single Readjuster senator caucused with them. As these elections were prior to ratification of the seventeenth amendment, senators were chosen by state legislatures.