MADISON, WI (WTAQ) - A group headed by Republican strategist Karl Rove has spent $3.8 million on behalf of U.S. Senate candidate Tommy Thompson.

Crossroads Grassroots Policy Strategy announced its latest ad campaign Tuesday, totaling $1.2 million.

It attacks Democrat Tammy Baldwin’s position on health care – featuring a sound bite in which she mentioned supporting government-run care. It’s the latest attack ad in a campaign full of them.

An ad tracking group in Washington said 92 percent of the TV ads in the Thompson-Baldwin race over the last month have been negative.

Baldwin leads the most recent independent polls by 3 to 4 points – close to a statistical dead heat.