A Virginia GOP official confirms to ABC News that Senator Allen will concede the race during a press conference scheduled for 3 o'clock eastern time this afternoon.
Yesterday an Associated Press survey tabulated the votes from Virginia's 134 localities and found that Democrat James Webb will win the state's U.S. Senate contest, giving Democrats the sixth seat they need to win control of the Senate and Congress.
The AP contacted election officials in all 134 localities where voting occurred, obtaining updated numbers Wednesday.
About half the localities said they had completed their postelection canvassing, and nearly all had counted outstanding absentees.
Most were expected to be finished by Friday. The new AP count showed Webb with 1,172,538 votes and Allen with 1,165,302, a difference of 7,236. Virginia has had two statewide vote recounts in modern history, but both resulted in vote changes of no more than a few hundred votes.
The independent call of the race by the AP -- a national consortium of news organizations -- will not affect the Virginia Board of Elections' tally.
"I'm going to leave predictions to pundits, and we're going to stick to the process and make sure the votes are tabulated accurately," James Alcorn, senor policy adviser for the Virginia Board of Elections, told ABC News.
Canvassing in Stafford County, Va., appears to have yielded some good news for the Allen camp.
Alcorn said he spoke to the precinct general registrar in Stafford County and learned Wednesday afternoon that Webb was expected to lose 1,312 votes there because of a human error.
Precinct officials had declared 1,969 votes for Webb late Tuesday night after a long count, Alcorn said. On Wednesday morning when they checked it again, the actual count proved to be 657.
Alcorn said it was the largest chunk of potentially swung votes he'd heard of yet.
Late Wednesday, the Allen camp issued "no comments" in response to the AP report.
Declaration Surprises Both Camps
AP's declaration appears to have caught both the Allen and Webb camps by surprise.
Canvassing began all across the state Wednesday as vote counts were checked and double-checked in each precinct and locality.
Hundreds of lawyers from both parties fanned out across the state to observe one of the most consequential vote counts in recent history.
"The closer the election, the more important these individuals are," said David Boies, who represented former Vice President Al Gore in the brutally contentious Florida recount of 2000.
While at least initially the lawyers will simply be observing the canvass -- the post-tally process of checking and double-checking vote counts, precinct by precinct -- a statewide recount could bring a host of election litigation.
Boies compared the process to "detective work."
"You just go precinct to precinct, and you try to see whatever you can find," he told ABC News' Law & Justice Unit. "You've got people going out doing detective work -- seeing whether someone made a clerical mistake, whether there are challenges to absentee ballots. … That is the ordinary stuff of election recounts."
Nevertheless, Boies said, being at the center of an election recount of such consequence is one of the most thrilling and humbling experiences in a lawyer's career.
"The primary emotion is excitement," Boies said. "That's why you become a lawyer -- because you're interested in the justice system, in making a difference in important cases, in developing the law, and making sure that people get to have their votes counted."
While the notion of lawyers flooding contested states to challenge elections may bring on an unpleasant electoral sense of deja vu in some, experts who spoke to ABC News agreed that the days ahead would be nothing like the mess that was Florida 2000.
"I do expect it will be a bit more orderly than Florida," said Dan Takaji, an Ohio State University law professor and an expert on election law. "The difference in Florida is that you had a large state with punch-card ballots and a number of big, urban jurisdictions. Those combined to make the process a mess. … We won't have the problem of ambiguously marked ballots."
Tuesday was the first time all Virginians who cast ballots in person used electronic voting machines in a general election.
Virginia uses DRE machines, optical scan and ballot-marking devices made by Diebold, Sequoia, UniLect, Advanced Voting Solutions, Hart InterCivic and ES& S.
Despite the use of electronic machines, Virginia did not require machines to produce a Voter Verified Paper Audit Trail, which could raise some questions about how a potential recount would be conducted and whether it would be difficult to obtain an unassailable vote count.
Boies pointed out other differences.
"The issue in Florida was whether or not a recount should go forward," he said. "Here both sides recognize that the other side has a right to a recount if they want one."
The vote-count margin in the Virginia race remains several thousand votes wide, with Webb in the lead -- while in Florida the margins were far smaller -- hundreds of votes in one of the most populous states in the nation.
"Virginia is not Florida," Jean Jensen, executive secretary of the state board of elections, told ABC News.
She said that the margin between Webb and Allen as of Wednesday afternoon was about 3/10ths of 1 percent, or 7,000 votes out of about 2.5 million.
Whoever wins the race could tip the balance of power in the Senate.
A recount would not begin until Nov. 28, an agonizingly long time to wait with so much at stake.
The canvass of Virginia precincts began Wednesday morning. Officials across the state are going over their numbers -- and counting provisional ballots -- to ensure accuracy.
They have seven days -- which started Wednesday -- to complete the canvass, though it usually takes no more than three days, state election experts told ABC News.
After canvassing, all the results go to the state board of elections, which meets on the fourth Monday in November, the 27th, to officially certify the results.
Once they are certified, a candidate may petition for a recount. He or she has 10 days to do so.
Jensen said that no recount petition in recent memory had been denied.
The recount would be supervised by a three-judge panel and take two weeks to three weeks, meaning future control of the Senate is not likely to be clarified until mid-December.
It may sound like an enormous amount of work, but both parties have been preparing for eventualities like this.
A team of lawyers and legal volunteers has been in place in virtually every competitive state for weeks -- a lesson learned after 2000.
"I think there are always lessons you can learn from any election," said Danny Diaz, spokesman for the Republican National Committee. "And clearly making sure every legal vote is counted is something that's important to our party and to our country."
Boies had some advice for Virginia's burgeoning election law teams on both sides.
"You want to have enough lawyers to cover every precinct to do your detective work," he said. "What you don't want is so many lawyers that either they begin to trip over themselves or they are so bored they start sitting around and coming up with creative litigation to win the race. You don't want to have lawyers dominate the process. You want to have lawyers help make the process work."