Obama used a visit to an auto plant in the cradle of the American labor movement to weigh in on the controversial push in the state legislature to impose new restrictions on unions, part of the Democratic president's political base that helped him win re-election last month.

"What we shouldn't be doing is trying to take away your rights to bargain for better wages and working conditions," he said to loud cheers from workers at the Daimler Detroit Diesel plant in Redford, Michigan. "We shouldn't be doing that."