If there's a ground zero in this presidential campaign, it might just be the parking lot of a downscale shopping center in North Columbus, Ohio, halfway between Papa John's Pizza and Payless Shoes.
Here, in the empty shell of a former Kohl's department store, Franklin County has set up an early polling station where voters can cast ballots without waiting for Election Day.
Ohio is the state each candidate covets most, the state most likely to tip the balance of electoral votes and anoint a winner. The most recent average of polls compiled by the Real Clear Politics website shows President Obama with a two-point lead in the state. But the GOP and its allies are pouring millions into last-minute advertising. Mitt Romney and Paul Ryan have spent more time in Ohio in the last few weeks than anywhere else - enough to prompt Obama to come back, and to bring Bill Clinton with him.
Columbus, the state capital, is a disputed region in a battleground state. The city votes Democratic, but its suburbs vote Republican. As of Friday, more than 133,000 Franklin County residents had voted early, either by mail or in person - almost one-quarter of the total number of votes cast there in 2008.
The Obama campaign says that's a good sign for them; early voters are more likely to be Democrats.
A poll conducted by Time magazine confirmed that. It found Obama and Romney tied among Ohioans who haven't voted yet - but showed Obama way ahead, 60 percent to 30 percent, among those who have voted already.
Republicans concede that Democrats have put more time and energy into urging their supporters to vote early. "I'm not sure how many of our people even know you can vote (early) in person," Scott Jennings, the Romney campaign manager in Ohio, told me.
But that doesn't mean Republicans are ceding any ground; GOP voters, Jennings said, are more likely to show up on Election Day or vote by mail. Still, in the last few weeks, Republicans have begun exhorting supporters to vote early too.
One afternoon last week, a shiny blue Romney campaign bus pulled into the Kohl's lot and disgorged half a dozen GOP luminaries, all female and led by Lt. Gov. Mary Taylor. They were met by exactly 13 Republican voters - plus six blue-shirted Obama supporters.
Three hours later, a second bus pulled up, this one carrying 28 students from Ohio State University. College Democrats lured them to the polls with cupcakes and four singing ukulele players.
The Obama campaign appears well organized, but it needs to be; this year's get-out-the-vote effort is an old-fashioned grind, a long way from the wave that swept the president into office in 2008.
In fact, the Obama campaign's biggest achievements in Ohio may have happened months ago. One was building a massive field organization in all 88 Ohio counties at a time when Romney and other Republicans were entangled in a bitter primary campaign.
The other advance, little noticed outside the state, was in a federal courtroom. Last year, Ohio's Republican-led legislature voted to restrict early voting days; Democrats sued to block the law's implementation, and won.
In an election this close, the decisive battles may not be over issues but over the rules. And they may not be over yet.
More than 1.6 million Ohio voters have requested absentee ballots this year, in part because of a decision by state officials to send an application to every voter. If some of those 1.6 million now decide to vote in person, they'll be required to cast provisional ballots - and their ballots won't be counted unless the election is close.
What that means, Ohio State law professor Edward B. Foley has warned, is that a candidate who falls just short on election night may ask for the provisional ballots to be counted, and that could take days. In 2008, Foley noted, about 207,000 provisional ballots were cast, enough to change a close election's outcome. The conventional wisdom holds that provisional ballots lean Democratic. This might be a scenario under which Obama could seek a longer count if election night doesn't go his way.
So if Ohio is as close on Election Day as it is now, this election could take much longer than one night to decide.
Readers can email Doyle McManus at firstname.lastname@example.org.