The Thompson ad played into his campaign theme trying to portray Baldwin as a liberal too extreme for Wisconsin. The debate moderator, veteran journalist Mike Gousha, asked Baldwin why she doesn't embrace the label, given that she's been voted one of the most liberal members of Congress.
Baldwin refused, and instead described herself as a "proud progressive."
Gousha then asked Thompson about comments he made during the hotly contested four-way GOP primary indicating that he was more conservative than people thought. Thompson backed away from those comments Friday.
"I've always been a moderate conservative," he said, adding that during his 14 years as governor he frequently worked closely with Democrats as well as Republicans.
On Iran, Thompson criticized Baldwin for voting four times between 2006 and 2011 against efforts to toughen sanctions. However, since Baldwin entered the Senate race, she has voted twice in favor of expanding sanctions.
He also criticized her for being one of 11 House members in 2007 to vote "present" on a resolution condemning Iranian President Mahmoud Ahmadinejad for questioning the Holocaust and advocating the destruction of the state of Israel. The resolution, which also called on the United Nations' Security Council to charge Ahmadinejad with inciting genocide, passed 411-2.
Baldwin questioned Thompson's holding stock worth about $38,000 in seven companies that do business with Iran. Thompson has said he's sold it.
"He should not be lecturing me on Iran policy," Baldwin said.
The "Tommy vs. Tammy" race in Wisconsin is the most expensive Senate contest in the state's history with spending from the candidates and outside groups topping $48 million. Baldwin, 50, has represented the Madison area in Congress since 1999. Thompson, 70, was first elected to the state Legislature in 1966 and served as governor from 1987 until 2001.
The Senate seat has been in Democratic hands since 1957, but due to the Kohl's retirement, it's viewed as a pick-up opportunity for Republicans as they try to win majority control in the Senate.