Just a couple of days after criticizing Sen. Rick Santorum for his 'pro-union' voting record during his time in the Senate, Mitt Romney had a slightly different tone in Michigan today saying they "play an important role in our society."

He went on to blast President Obama for his close ties to unions. 

Last week, Romney's campaign sent out memos stating, "I won't give in to the UAW" while calling Santorum "big labor's favorite Senator."

Romney is referring to Santorum's votes in the Senate against national right-to-work and in support of the Davis-Bacon Act - which requires government contractors to pay the prevailing wage.