Wisconsin's largest business association is attacking a Democratic state Senate candidate for proposing a gas tax increase even though the group has supported an increase for months.

Wisconsin Manufacturers and Commerce's political advocacy arm has been running a television ad blasting Winnebago County Executive Mark Harris for proposing a gas tax increase. Harris told Wisconsin Eye last month that he supports a 3-cent increase in the tax to help fund roads.

WMC President Kurt Bauer wrote on the association's website in December 2014 that the simplest way to fund roads is through a "modest" gas tax hike and increasing vehicle registration fees. Harris' opponent, Republican Dan Feyen, told Wisconsin Eye in July that he would be open to a 5-cent gas tax increase.

WMC officials had no immediate comment.