Perception.

It's a funny thing in elections. For months, reality doesn't matter as much as the perception of it. Who's ahead? Who's behind? No one really knows. Then, on Election Day, perception is tossed aside as the cold, hard reality of votes being cast comes crashing down.

But that decisive moment is months away in Virginia, where Democratic Lt. Gov. Timothy M. Kaine and former Republican attorney general Jerry W. Kilgore are coiled tightly for the final sprint to Nov. 8.

So, for now, it's all about how the candidates are perceived by voters, pundits, reporters and each other.

Those perceptions have been shifting quickly.

Earlier this summer, it seemed Kaine had an edge.

A fundraiser with Gov. Mark R. Warner netted more than $1 million for the lieutenant governor, giving him a big boost in the early money race. Unlike most Democrats, Kaine found himself in the position of having raised more money than Kilgore.

More recently, however, Kilgore has seemed to take some of that advantage back.

Kaine's proposals for solving the state's transportation problems were greeted with a huge yawn by road and transit advocates. They included no promise of big bucks and would do little to change the frustrating dynamic in Virginia of too many needs and no way to meet them. His big idea: to travel the state after being elected to assess the problem.

Kilgore's edge continued into mid-July, when he did unexpectedly well at the first major debate with Kaine.

Perhaps it was the belief that Kaine would trounce the less-than-comfortable Kilgore. When that didn't happen, the all-important perception was that Kilgore had "won" the debate.

The Kilgore campaign did everything it could to stoke that perception. Even before the debate ended, a Kilgore operative sent an e-mail saying merely: "My boy is on fireeeeeeeeeeeeeeeee."

Kilgore followed with a record-breaking $2.1 million fundraiser with President Bush that evened the money race.

But now, with about three months to go, Kaine has reclaimed a sense among those who watch these things that he's on the road to success.

How?

The Mason-Dixon poll, commissioned by several Virginia news organizations, stunned observers by showing Kaine leading Kilgore among likely voters, 38 percent to 37 percent. Like the debate, the poll confounded the conventional wisdom and gave the impression -- real or not -- that Kaine had surged.

The Kaine folks seized on the news. In a letter to supporters, campaign manager Mike Henry wrote that the poll "shows what we've known all along -- in the race for Virginia Governor, Tim Kaine clearly has the momentum, as voters are becoming more and more convinced that he is the best candidate to keep Virginia moving forward."

Ken Hutcheson, the Kilgore campaign manager, wrote a similar letter to his Republican supporters trying to repair the damage. "This poll flies in the face of everything we have seen," he wrote. "Everything we see places the momentum squarely on our side."

So who's right?

It's impossible to tell. On the one hand, the Mason-Dixon poll is the most respected, and well-designed, of the polls to date. Other surveys showing Kaine down by 5 to 10 points were automated telephone polls of dubious design. So it's possible that Kaine really is ahead.

On the other hand, both campaigns have done internal polls in the past few months that show Kilgore leading. And the Mason-Dixon poll had a margin of error of plus or minus four percentage points. That means it's just as likely that Kaine is trailing by three points as it is that he's leading by one.

At this point, it really doesn't matter what the reality is. The perception, for now, is that Kaine is surging and that the race, as most newspapers declared after the poll, is a dead heat.