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When I was on the road in 2007 covering the 2008 Republican presidential race, I ran into the journalist Sasha Issenberg and asked him who he thought would win. “McCain,” he told me.

It was a stunning answer at the time. John McCain trailed badly in the polls, had fired much of his original campaign staff and didn’t have much money. But Issenberg predicted that every other candidate in the race was too flawed and that Republican voters would eventually come back around to the campaign’s original front-runner: McCain. Sure enough, they did.

I’ve thought about that conversation during Joe Biden’s rise over the past four days. The race isn’t over; Bernie Sanders could still win the nomination. But Biden is now the favorite, amazingly enough.