(CBS News) LEESBURG, Va. -- The latest poll in Virginia shows the presidential race there is a virtual tie. A poll conducted by NBC, The Wall Street Journal and Marist Poll put President Barack Obama one point ahead of Gov. Mitt Romney, 48 to 47 percent -- well within the margin of error.
That means every voter behind every door counts.
If you live in Virginia, the race for the president of the United States has become a race to the front door. It's a ground game sprint by both campaigns to knock on hundreds of thousands of doors to plead with their own supporters to show up on election day.
Romney volunteer Mackie Christenson in Leesburg, Va., said the ground game is in a way closing the deal.
"We need the vote. We need the vote," she said. "It is so close, we know it's close. You know, we listen to the polls."
Nearby in Gainesville, Va., Obama volunteers Linda Legarde and Taylor Tuckerman were urging the president's supporters not to get distracted or forget to vote.
Tuckerman said that even though the Americans they talk to are supporting the president anyway, knocking on doors hours before Election Day still has a point.
"The point is to remind them that their vote counts. They could be the one that flips it for our side, their vote could be the one that helps make a difference," Tuckerman said.
The in-person visit did make a difference to Obama voter Stephanie Torres.
"I think it does give it a personal touch," Torres said. "I think it does solidify your own position."
Every step taken by these volunteers is science.
The campaigns, after making millions of phone calls, already know who has voted early, so they know with house-by-house precision where their likely voters remain.
That precision means the door knockers are given maps showing not just whom to contact, but the most efficient way to walk there.
"It tells us where to start and where to end," Christenson said, pointing to a map.
Most of the voters like Zach Gelnett -- a Romney supporter -- have been visited 3 or 4 times.
"I get a ton [of phone calls], especially on my home office phone, I get 6 or 7 a day," Gelnett said.
But both campaigns now believe Virginia will be decided by the better ground game.
After the candidates spent $86 million here on ad time, and hundreds of hours in campaign time, Virginia comes down to face time.