In 1894, Fairbanks was the most visible organizer and speaker on behalf of Republicans in elections for the state legislature. He was credited with delivering Republican majorities to both the Indiana House of Representatives and Indiana Senate, ensuring that a Republican would be elected to succeed Daniel W. Voorhees in the United States Senate at the end of Voorhees' term in 1897. At the 1896 Republican National Convention, Fairbanks was both temporary chairman and keynote speaker, further raising his public profile. Fairbanks was the most likely Republican candidate for Voorhees' seat, and in January 1897 Republican legislators formally chose him as their nominee. On January 19, 1897, Fairbanks was elected to the Senate, and he took his seat on March 4.