Posted: Tuesday, November 6, 2012 --- 8:49p.m.

MADISON, Wis. (AP) -- Republican Tommy Thompson has an early lead over Democrat Tammy Baldwin in the race for the U.S. Senate in Wisconsin.

Returns tabulated Tuesday by The Associated Press show Thompson up by about 10 percentage points with roughly 4 percent of precincts reporting.

Baldwin is vying to become the first woman senator from Wisconsin. She would also be the first openly gay candidate elected to the Senate.

Thompson is on the ballot for the first time since 1998 and trying to flip the Senate seat to Republican control for the first time since 1957.

The campaign was the most expensive ever for a Senate seat in Wisconsin and featured a barrage of negative advertising.

The vacancy was created by the retirement of Democratic Sen. Herb Kohl.

Copyright 2012. The Associated Press.