But once the two candidates met on an equal footing in Denver, many voters were amazed to meet a Romney who seemed like an earnest businessman looking for ways to fix the economy — a Romney who insisted that, contrary to his previously stated positions, he didn't want to cut taxes for the wealthy, abandon healthcare reform or reduce education spending (issues that polls find especially important to female voters).
Equally important, voters saw an incumbent president who, after reading last month's lopsided polls in his favor, appeared to think he didn't need to refresh his year-old talking points or break a sweat in his rebuttals.
The result was a debate that not only showed Romney at his best but reminded voters of Obama's biggest vulnerability: that the economy is still ailing nearly four years into his term.
And that's what produced this week's remarkable poll numbers, and a reprieve from conservative conspiracy theories charging that the pollsters were cooking their numbers to make Obama look good.
Before last week's debate, historians and pundits warned that debates rarely change the course of a campaign. This time turned out to be one of the exceptions. Obama needs to hope next week's rematch also defies expectation and changes minds — this time with him as the beneficiary. But to do that, he's going to need more than just crisper rebuttals to Romney's best zingers.
He'll need to remind swing voters why they once admired him.
He'll need to make his economic plan sound fresh and promising.
He'll need to present himself in a way that makes swing voters take a second look.
In other words, he'll need to do just what Romney managed to do in Denver.
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Follow Doyle McManus on Twitter @DoyleMcManus