Baldwin outlasts Thompson, wins open Wisconsin Senate seat

Washington (CNN) - After seven terms in the House, Democrat Tammy Baldwin has defeated Former Gov. Tommy Thompson in the race for Wisconsin's open Senate seat, according to CNN's projections.

Though polling had the election close through most of the race, Baldwin defeated Thompson 51% to 46% with 78% reporting.

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Baldwin, along with outside groups, spent a lot of their advertising painting Thompson as someone who left politics to cash in on lobbying. Both Democrats and Republicans officials acknowledge that the attacks drove Thompson's negatives up – and led to a testy campaign tone.

In total, the race cost over $73 million, according to the Center for Responsive Politics. Outside groups, on their own, spent over $45 million.

The Wisconsin Senate seat opened up when Sen. Herb Kohl retired after four terms in the Senate. Thompson, who won a four way primary for the Republican nomination, was Baldwin's first competition in the race – she ran unopposed for the Democratic nomination.

The election win makes Baldwin the first openly gay member of the Senate.