Posted Friday, July 13, 2012 --- 6:10 a.m.

MADISON, Wis. (AP) -- The conservative Club for Growth is going after both former Gov. Tommy Thompson and hedge fund manager Eric Hovde in its latest attack ad.

Polls show Thompson and Hovde are leading the four-person field in the Republican race for the U.S. Senate. The anti-tax Club for Growth has endorsed former U.S. Rep. Mark Neumann in the race. State Assembly Speaker Jeff Fitzgerald is also running.

The latest ad running statewide starting Friday attacks Thompson's record as governor, saying he pushed for nine different tax hikes as governor. It then goes after Hovde, calling him "like Thompson, only worse."

It cites Hovde's $500 donation to former Democratic Gov. Jim Doyle, who raised taxes during his eight years in office.

The GOP Senate race primary is Aug. 14.

Copyright 2012. The Associated Press.