DETROIT (AP) — Only a couple of weeks after Barack Obama won the presidency in 2008, the man who would become his Republican challenger in the next election penned a New York Times column with a fateful headline: "Let Detroit Go Bankrupt."

Those four words would haunt Mitt Romney across the Rust Belt, where auto manufacturing remains an economic pillar. They were especially damaging in Ohio, a state that every successful GOP presidential nominee has carried, and in Romney's home state of Michigan, where his father was an auto executive and governor.

Romney's opposition to the federal rescue of General Motors and Chrysler didn't necessarily seal his fate in those two crucial states. But no other issue hung in the background for long. And nothing that Romney tried could overcome it.