DANVILLE, Va.-- In the hot stillness of a mid-August afternoon, two volunteers for Sen. Barack Obama are standing outside a convenience store in one of Danville's poorer neighborhoods, asking the people who exit and enter if they're registered to vote.

Yes, say some. Others shake their heads and walk inside, the screen door banging behind them. Still others mutter that they can't vote because they have criminal records. Finally, though, one woman stops and hesitates. Come to think of it, she says . . .

Instantly, forms are offered, pens are brandished, and, while politics never comes up -- such discussions aren't allowed, under the law -- the volunteers are smiling.

One down, only 85,000 more to go.

It's a long, slow haul, this business of registering voters, but 85,000 is how many more Virginians Mr. Obama needs to register in order to reach 150,000 -- the number he has vowed to add so he can become the first Democratic presidential candidate to carry the Old Dominion since Lyndon Johnson in 1964.

It's either foolhardy or a stroke of genius, a holdover strategy from the primary season, when the Illinois senator's campaign hunted down voters wherever they could find them.

Long a bastion of Republican conservatism, Virginia, the only southern state that Jimmy Carter didn't win in 1976 -- he lost by one percentage point -- is in play this year, a toss-up, dead even in the polls, a state whose political coloration has morphed from red to a very light shade of blue.

Although the state went for President Bush by 8 percentage points in 2004, Democrats have been doing well in state races. In 1989 Virginia elected the nation's first black governor, Democrat Doug Wilder, albeit by a tiny margin, and in the past decade it elected two successive Democratic governors and a Democratic senator. It now appears headed toward electing a second one.

Can Virginia help elect a Democratic president?

The Obama campaign believes it can -- and must. The very fact that the campaign has opened an office in Danville -- something Democrats have rarely bothered to do in past presidential campaigns -- is seen as a sign that Mr. Obama is serious.

"We're going after people who are persuadable, people who may be likely Obama supporters, sporadic voters, undecideds," says Adam Broad, an Obama organizer, noting that the city of Danville is nearly 50 percent African American, with a smattering of young college students besides. "We persuade, we mobilize, and we register. That's what we do."

The political calculus is simple: If Mr. Obama wins every state Sen. John F. Kerry won in 2004 and just two more, one of them Virginia, he'd get the 270 votes needed to win the election. Mr. McCain, on the other hand, would have to win a big state like Pennsylvania or Michigan if he loses Virginia.

So, as part of a Southern Strategy, the Obama campaign is targeting Virginia's 13 electoral votes, along with North Carolina's and Georgia's. Ads are up on television and the campaign has opened 33 offices, from Arlington to Culpepper to Danville, the former -- and final -- capital of the Confederacy, where Jefferson Davis was rumored to have hidden under a bed until the victorious Union soldiers caught up with him.

The area has been struggling to regain its economic footing -- with some success -- after the collapse of the tobacco and textile industries in recent decades, and may be receptive to Mr. Obama's message of change.

Or not.

"I think they're being very optimistic," said Gordon Caperton Morse, a contributing editor at The Daily Press in Williamsburg. While Democrats have attracted moderate Republican voters to win state races, "when you get to the big four-year presidential election, the old patterns kick in."

For both candidates, Virginia may come down to a battle over margins rather than all-out victory in one region or another. Mr. Obama will probably win Northern Virginia and Richmond, Norfolk and Charlottesville, while Mr. McCain is claiming territory in the west and south around Danville -- which borders North Carolina in Virginia's "Southside" -- along with the predominantly agricultural Shenandoah Valley and southwest Virginia's mining communities.

Here, a conservative Southern culture remains resistant to Democratic candidates -- at least those on a national level. While the city went for Mr. Kerry in 2004, the surrounding counties went overwhelmingly for Mr. Bush.

But those regions also present an opportunity for Democrats, said Mr. Morse, who recalled former Gov. Mark Warner campaigning at NASCAR rallies with a bluegrass band in tow.

"It was utterly contrived," he said, "but it was clear what Warner was doing, and he held down votes which would have automatically gone to Republicans. Can Obama do that? I don't know."

While Northern Virginia's affluent, well-educated high-tech and government workers are helping to turn a red state blue, Mr. McCain's image as a moderate and a maverick may keep Mr. Obama's victory margins down in Northern Virginia, contended U.S. Rep. Tom Davis, of Fairfax County.

Mr. McCain and Mr. Obama will also be battling hard in the Hampton Roads area, with its high population of veterans and active military -- one of only two areas in the state up for grabs, along with some Richmond suburbs, that have seen an influx of moderate voters down the I-95 corridor from Washington, D.C.

In the Tidewater region, the population is 20 percent black -- but with nine military bases in the region, including the largest Naval base in the world, there's also a high concentration of veterans and active military. But the war in Iraq may yield some unexpected results, said Mr. Morse.

"The military vote is the most fascinating aspect of this thing," he said. "There is an enormous amount of ambivalence about Iraq among people there. They feel abused, jacked around. They never know when a loved one is coming home or not. That's going to be a factor, and McCain may suffer as a result."

Paul Galanti, who was a prisoner of war in Hanoi with Mr. McCain and who heads Virginia Veterans for McCain, doesn't see it that way.

"John McCain is loved by the military in this state," he said. "He understands the way we think. Obama is not going to win in Virginia, because he hasn't done anything. He has no experience."

Certainly, in the modest neighborhoods around Hampton, McCain signs proliferate, "but that's because we haven't put the Obama signs up yet," joked Ellis James, a volunteer with the local Sierra Club chapter.

Hampton tends to split its vote, while Norfolk is Democratic, and Virginia Beach, a former Republican stronghold, voted for Gov. Tim Kaine, a Democrat, in 2005.

Still, local fervor for Mr. McCain seems strong in Virginia Beach, whose tourism industry has taken a major hit this year because of high energy prices. At a McCain-campaign-sponsored news conference/roundtable of small businessmen at the Black Angus restaurant last week, the room bristled with frustration over increased energy costs, and continued Democratic opposition to offshore drilling.

Mr. McCain's plan for energy independence -- which includes increased drilling and nuclear power -- was the answer, declared George Allen, the former Virginia governor and senator, who led the roundtable.

"We're sick of being jerked around by the oligarchs, cartels and dictatorships," said Mr. Allen, who lost to Democrat Jim Webb two years ago after some well-publicized gaffes but who remains popular with Virginia conservatives and the GOP faithful. The Democratic proposals, he added, "are like going back to the Carter era. All it did was make us more dependent on foreign oil."

Still, Mr. McCain's political director, Michael DuHaime, acknowledged for the first time last week that the race in Virginia will "undoubtedly be close" -- a shift from June, when the campaign described the state as solid for Mr. McCain. Mr. DuHaime noted that on Thursday, 90 house parties for the Arizona Republican were held all around the state, and the campaign is recruiting more than 1,000 precinct captains.

"Obviously, Sen. Obama is putting an awful lot of money into Virginia, both on the ground and on television, and it is a state that has elected Democrats recently," said Mr. DuHaime in a conference call with reporters. "But it's one we take very seriously and one we think still leans for us and one we will fight for every single day."

Mr. Obama's three-pronged strategy -- register new voters, increase turnout and target undecideds -- could also be boosted by the "reverse coattails" effect of former Gov. Mark Warner, whom Mr. Obama selected as the keynote speaker at the Democratic Party's convention and is widely expected to win retiring Republican John Warner's U.S. Senate seat this fall.

Mitchell Stewart, Mr. Obama's state director in Virginia, didn't disagree with that assessment.

"It's really remarkable how extremely popular Mr. [Mark] Warner is," said Mr. Stewart, noting, however, that "both Mr. Obama and Mr. Warner are going to Washington to change it."

Just after securing the nomination in June, Mr. Obama traveled to the coal-mining country of Bristol in southwest Virginia, not a region seen as particularly hospitable to his candidacy, but a sign, Mr. Stewart said, "that we intend to fight for every vote. We're fighting everywhere."

Still, there's some skepticism that Virginia will play the deciding role in the election, even if Karl Rove wrote recently that it would -- along with Colorado, Ohio and Michigan.

"Obama can carry Virginia but it won't be the state that puts him over the top," said Mr. Davis, the northern Virginia congressman, noting that "other, larger national forces will have to be in play for Obama to win. Virginia won't do it for him."

Moreover, voters aren't blaming John McCain for the economy any more than they think Mr. Obama can fix it.

"Obama isn't an economic candidate," he said. "He is a cultural candidate. He's a Harvard guy, not a down and dirty guy. He'll take the college towns, the African Americans, the urban affluents, but he won't take Harry Hunter. He can't even bowl."

Still, as of this week, at least, Virginia could go either way -- depending on any number of factors, from the price of gas to unrest overseas. While Mr. Obama hopes to woo moderate Republicans like Philippa "Flip" Bowers, 76, of Charlottesville, she says she is wavering.

"A month ago I would have said I'm voting for Obama, but now I'm not sure," said Mrs. Bowers, a lifelong Republican who worked in Ronald Reagan's White House. "I voted for Bush twice, and I'm disappointed. He doesn't seem to be engaged."

But, she wondered, "Does Obama have the experience? This business with Russia and Georgia made me think about that. At this point, I just don't know."