The 1912 United States Senate elections took place on December 12, 1911 (certified in 1912) and March 27, 1912 (special election). This marked the first U.S. Senate elections held in Arizona after it was admitted to the union.
Henry F. Ashurst was elected to the Territorial House of Representatives in 1897. He was re-elected in 1899, and became the territory's youngest speaker. In 1902, he was elected to the Territorial Senate. In 1911, Ashurst presided over Arizona's constitutional convention. During the convention, he positioned himself for a U.S. Senate seat by avoiding the political fighting over various clauses in the constitution which damaged his rivals. With the admission of Arizona as a state in 1912, Ashurst was elected by the Arizona legislature as one of the state's two Senators, taking office on April 2 alongside Marcus A. Smith.
Marcus A. Smith announced his candidacy for one of Arizona's two senate seats on September 24, 1911 As the campaign began, Smith abandoned his long standing conservative stand and declared himself a "Progressive". The Arizona State Legislature confirmed the selection of Smith and Ashurst as the state's first U.S. Senators on March 27, 1912.