Posted Thursday, February 9, 2012 --- 2:51 p.m.

MADISON, Wis. (AP) -- A business-backed trade group is launching a statewide ad against U.S. Rep. Tammy Baldwin.

The ad launched Thursday is paid for by the U.S. Chamber of Commerce. The group isn't saying how much it's spending.

The group is targeting Baldwin, so far the only Democrat running for U.S. Senate this year. The commercial accuses her of wanting to raise taxes and over-regulate small businesses.

Chamber officials say this is the earliest in an election year that the 100-year-old organization has begun "voter education" efforts.

Baldwin spokesman Phil Walzak says that shows how afraid the group is. He says it's clear Baldwin's middle-class message is resonating with Wisconsin voters.

Former Wisconsin Gov. Tommy Thompson, former U.S. Rep. Mark Neumann and Assembly Speaker Jeff Fitzgerald are running for the GOP nomination.