Outside groups spend big on WI Senate race - WKOW 27: Madison, WI Breaking News, Weather and Sports

MADISON (WKOW) -- Outside groups are spending big in Wisconsin's U.S. Senate race, to the tune of a combined $8.8 billion according to a tally by the nonpartisan Center for Responsive Politics.

That's the third most spending on any race in the nation behind the presidential race and a U.S. Senate race in Texas.

The Center for Responsive Politics found the money is coming in 3-to-1 for ads that would help Democratic Congresswoman Tammy Baldwin. She faces Republican and former Wisconsin Governor Tommy Thompson in the November general election.

Just this week, conservative Karl Rove's political action committee, Crossroads GPS, made a $961,000 ad buy targeting Baldwin, adding to the $500,000 the group has previously spent on anti-Baldwin ads in this race.

The candidates are scheduled for three televised debates before the election.