Sen. John Waterman has lost his seat to challenger Eric Bassler.
With 98 percent of precincts reporting, Waterman has 400 fewer votes, according to numbers from the Secretary of State.
Waterman has 49 percent of the votes compared to Bassler’s 51 percent.
The Indiana Chamber of Commerce endorsed Bassler, who is a Washington city councilman, instead of Waterman, who is the incumbent.
The chamber opposed Waterman largely because of the state senator’s vote in opposition to right to work in 2012.
This is the first time Waterman has been up for election since that vote.
No Democrat ran in Tuesday’s primary, but the Democratic Party could still choose a nominee before the general election in November.
Correction: An earlier version of this story switched the percent of votes each candidate had received.