He was elected as a Republican to the
Sixty-first Congress, and served from March 4, 1909, to March 3, 1911, representing Washington's newly created
3rd congressional district. He was reelected in 1910, but resigned in 1911 because the
Washington State Legislature elected him to the U.S. Senate. He was reelected in 1916, and served from March 4, 1911, to March 3, 1923. Poindexter left the Republican Party in 1913 to join the
Progressive Party, rejoining the Republicans in 1915. During World War I, Poindexter moved away from supporting progressive causes and led several efforts that questioned the patriotism of German-Americans and attempted to keep them from wartime leadership positions in the military. In a highly publicized instance, Poindexter accused German-born Colonel Carl Reichmann (1859–1937), a distinguished Army officer who had served since 1881, of being pro-German and used the legislative process to block Reichmann's promotion to brigadier general. Reichmann had become a US citizen in 1887 and the promotion was supported by
American Expeditionary Forces commander
John J. Pershing,
Hugh L. Scott, the
Army Chief of Staff, and
Newton D. Baker, the
Secretary of War, but they were unable to overcome Poindexter's opposition and Reichmann remained a colonel. Poindexter also played a role in instigating the
First Red Scare by accusing the Wilson administration of being infested with Bolshevism and accusing
United States Supreme Court Associate Justice
Louis Brandeis of being a communist. Poindexter was a target of reformers and progressives in 1922, and lost his bid for reelection to the Democratic nominee, Representative Clarence Dill. ==Committee chairmanships==