Early in 1876, Speaker Kerr was seized with fatal illness and Cox served as acting Speaker on occasion. Cox was ultimately named Speaker "pro tem" on June 19. However, Cox left the capital to serve as a delegate to the 1876 Democratic National Convention, and Milton Sayler was chosen to fill the Speakership. When Cox returned, Sayler did not relinquish the chair. After Kerr's death, Randall was elected his successor in the 45th Congress and Cox was additionally placed at the head of the committee on the Tenth Census. Though Cox had loyally supported Democrat Samuel Tilden over Rutherford B. Hayes and implicitly given his support to the special committee's bill, he gave a speech urging the House to accept Hayes as the victor.