The 1881 United States Senate election in Wisconsin was held in the 34th Wisconsin Legislature Incumbent Republican U.S. senator Angus Cameron did not run for re-election. Republican former U.S. representative Philetus Sawyer was elected on the first ballot.
In the 1881 term, Republicans held overwhelming majorities in both chambers of the Wisconsin Legislature, so had more than enough votes to elect a Republican The main contest was in the Republican legislative caucus, but the former U.S. representative, Sawyer, was quickly nominated after demonstrating a clear majority of support.
Prior to the 1880 legislative elections, Sawyer made it clear that he was seeking to succeed Angus Cameron as , supporting allies in legislative nominating contests throughout the state. After the election, Sawyer was projected to easily achieve a majority of the caucus on the first ballot. Those predictions were confirmed when the Republican caucus met on January 19, 1881. An informal poll found a clear majority for Sawyer's nomination, and the caucus then chose to formally recognize him as their nominee by acclamation.
The 34th Wisconsin Legislature met in joint session on January 26, 1881, to elect a U.S. senator. The voting went almost exactly along party lines, with three members absent. Of the members present and voting, Philetus Sawyer received the votes of all but two Republican legislators, winning the election.