Almost every poll released since the first presidential debate has shown Romney making up ground. In the first poll taken after 67 million people watched the Denver contest - the biggest debate audience since 1992 - Pew, which had one of the two most accurate polls in 2008, showed a 12-point turnaround for Romney, from an 8-point deficit to a 4-point lead. Romney now leads in Florida, is basically tied with Obama in Virginia and Colorado, and has narrowed the president's lead in pivotal Ohio.
All eyes are on that state and its 18 electoral votes. No Republican has ever won the presidency without Ohio, and Romney has been campaigning there relentlessly. With three weeks to go, Romney now has a fighting chance to succeed at that and the historically difficult task of defeating a sitting president seeking reelection.
For the Obama campaign, one advantage of the vice presidential debate was that it allowed Biden to road-test attack themes leading up to tonight's pivotal town hall-style presidential debate. The Obama campaign faces a perilous choice in this second faceoff: aggressively attack Romney, or play as if it has the lead.
The Obama campaign simply cannot allow another disengaged performance: As one Democrat recently complained to me, Obama didn't lose the first debate; he forfeited it. However, the format of this debate, with voters asking the questions, will make it harder for the candidates to engage each other directly. Pointed attacks may appear unseemly in the kind of debate in which Bill Clinton's "feel your pain" approach famously excelled.
And if Obama attacks, he can expect his opponent to be ready for it. Romney has demonstrated thorough preparation and command of the issues, having won the first debate on both substance and style. He was better prepared, more poised and confident, and able to accomplish exactly what he needed to. Most important, he showed the television audience that he was not the caricature that Obama's negative ads had made him out to be. Can the president possibly trust his own preparation considering the result in Denver?
Tonight's debate will be about whether the president can change the narrative. Next week's third and final debate, on foreign policy, is sure to focus, among other things, on questions about a potential cover-up after the terrorist attack on U.S. officials in Libya last month.
In the end, though, this election will come down to Ohio and Virginia. If Romney can win both by peaking at the end and taking advantage of an enthusiasm gap, he will win the presidency. That result may have seemed unlikely three weeks ago, but it's now within his reach.
Matt Mackowiak is a Republican consultant based in Austin, Texas, and Washington, and the president of Potomac Strategy Group. He has been an adviser to two U.S. senators and a governor, and to national and state campaigns. He can be reached at firstname.lastname@example.org.