Mitt Romney's gloves were already off before Friday, but he took another swing at Barack Obama upon the president's visit to Ann Arbor.

In an open letter to Obama, which is being published in the Detroit News and the Detroit Free Press, Romney says he has one question for Obama: Where are the jobs?

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Mitt Romney

From there, the letter turns political.

"Mr. President, forgive me for being blunt, but when it comes to economic affairs, you're out of your depth," Romney writes. "Unlike you, I am not a career politician. Unlike you, I’ve spent more than two decades working in the private sector, starting new businesses and turning around failing ones. Undoing the damage you've done will be a daunting challenge."

Many political observers are looking forward to a Romney versus Obama matchup in the 2012 presidential race. But in Michigan, Romney will be forced to defend a New York Times editorial titled "Let Detroit Go Bankrupt" that he published during the auto crisis.

"If General Motors, Ford and Chrysler get the bailout that their chief executives asked for yesterday, you can kiss the American automotive industry goodbye," Romney wrote in that November 2008 piece.

Of course, that hasn't happened, and Obama reminded the crowd of that at the University of Michigan today, making a thinly veiled slam at Romney without using his name.

"Some politicians were willing to let this die," Obama said at the Al Glick Field House. "We said no — we believe in the workers of this state. I believe in American ingenuity."

Ryan J. Stanton covers government and politics for AnnArbor.com. Reach him at ryanstanton@annarbor.com or 734-623-2529. You also can follow him on Twitter or subscribe to AnnArbor.com's email newsletters.