The 1906–07 United States Senate elections were elections for the Class 2 Senate seats in which the Republican Party gained three seats in the United States Senate, expanding their majority to more twice that of the opposing Democratic Party. The elections were held alongside the 1906 House of Representatives elections, which saw a significant Democratic gain in contrast to the Senate elections. As these elections were prior to ratification of the seventeenth amendment, Senators were chosen by state legislatures.