MADISON, Wis. (AP) -- Former U.S. Rep. Mark Neumann has conceded in the Republican Senate race and endorsed Tommy Thompson.

Thompson and businessman Eric Hovde were leading in the four-person race Tuesday that was too close to call based on early returns. State Assembly Speaker Jeff Fitzgerald has also conceded.

Neumann told his supporters that their work is not done and he encouraged them to help defeat Democratic Senate candidate Tammy Baldwin.

Neumann calls Baldwin "somewhere out to the left of Barack Obama in never never land."

The Republican race was the only statewide contest in Tuesday's primary. The seat is open due to the retirement of Democratic Sen. Herb Kohl.