Oversight boards and receivers have for decades been assigned to help shore up some of the nation’s most financially troubled cities, and more than 20 state emergency managers have been assigned in Michigan over the last quarter century. But the challenges — political, racial and economic — of running a city like Detroit are immense. Its problems, arising in part by the decline of the American auto industry and the resulting loss of more than half of Detroit’s population, have been decades in the making. But an emergency manager could get as little as 18 months to fix them.

“I think it’d be like a double root canal,” Pat O’Keefe, a Detroit-area financial consultant who has dealt with municipal turnarounds, said of the assignment.

Under a revised state law governing emergency managers that will go into effect on March 28, the same week that Mr. Orr is to begin his job, he will be granted sweeping powers to remake the city’s financial plan, change labor contracts and sell city assets. He will make $275,000 a year, nearly all of it paid by the state, and may choose to hire staff to be paid for by the city. Many of his decisions will trump those of elected officials, although some leaders — most notably Mr. Bing — have indicated a willingness to collaborate with Mr. Orr.

Despite Mr. Orr’s legal background, he said he hoped the city would not ultimately need to file for bankruptcy. Municipal bankruptcies are rare, but it was lost on no one that the state had selected an expert in bankruptcy law for Detroit, as opposed to a financial accountant, former city manager or elected official. Under Michigan law, a city can file for bankruptcy only under certain conditions, including if an emergency manager has attempted other measures and concluded that such a move is needed.

For now, Mr. Orr said he was hopeful that he could move quickly, perhaps faster than expected. Solutions, he said, can come “as quickly as anybody is ready to make a deal.”