They had 99 problems but Mitt Romney wasn't one. At the start of an epic election, the team trying to reelect President Obama faced a mountain of challenges: a dismal economy, the faded hopes of the first campaign, and a struggle to raise enough cash to compete. No president had risen so fast, or fallen so far, in the modern era. And no president in living memory had earned a second term in such troubled times. To resell the president, they...