Baldwin defeats Thompson in Wis., becomes first openly gay senator

Rep. Tammy Baldwin (D-Wis.) has defeated former Wisconsin Gov. Tommy Thompson (R), making her the first openly gay senator in U.S. history.

The win is a huge one for Senate Democrats, who appear to be heading toward a big night. Reuters and Fox News have called the race.

Thompson had led in early polls, but finished his August primary exhausted and with little money. As he took a break from campaigning, Baldwin and Democratic groups flooded the airwaves with ads criticizing on his time working for Washington, D.C.-based pharmaceutical groups after he stepped down as Health and Human Services secretary.

The attacks worked: Thompson went from a comfortable high single-digit lead in public polls to trailing by the same margin within the month. National Republicans sent in staffers to overhaul his campaign and conservative groups counterattacked with ads painting Baldwin as an uncompromising liberal, but the attacks were too little, too late.

Baldwin is one of the most liberal House members. She will replace retiring Sen. Herb Kohl (D-Wis.).