Wisconsin Republican Tommy Thompson says he has filed paperwork allowing his U.S. Senate campaign committee to raise and spend money on his behalf.
Thompson said in an email to supporters Tuesday that he filed his statement of candidacy with the Federal Election Commission. He incorporated his campaign committee last month.
He has not formally announced his candidacy despite hiring campaign staff, announcing supporters and raising money.
Thompson says he also signed the Taxpayer Protection Pledge that commits candidates and office holders to oppose all net tax increases.
Former U.S. Rep. Mark Neumann was the first Republican to enter the race in Wisconsin to replace retiring Democratic U.S. Sen. Herb Kohl. Assembly Speaker Jeff Fitzgerald and state Sen. Frank Lasee have also filed FEC paperwork, but have not formally announced.