For most of the year, the race for Virginia's open Senate seat has been a dead heat. The candidates, former governor Tim Kaine and former senator George Allen, draw even support from the public, and neither has managed to reach the large number of undecided voters. But, if yesterday’s poll from NBC and Marist is any indication, Kaine has pulled away from Allen with a six-point lead, 49 percent to 43 percent.

He wins 50 percent of women, 55 percent of voters under the age of 45, 68 percent of non-white voters and only 41 percent of whites. He dominates in the D.C. suburbs, winning 66 percent of the vote, performs well in Northern Virginia and the Richmond area — tying Allen with 46 percent support — and holds on to a 53 percent majority in the Tidewater/Hampton Roads area.

What’s interesting is that this is nearly identical to what Marist found in its survey of the presidential race in Virginia, with a few differences. Obama wins a smaller portion of white voters, 38 percent, and beats Kaine by 3 points in the Tidewater area. Overall, he wins 48 percent support to Romney’s 44 percent. Obama’s isn’t far away from his performance in the 2008 election, where he won Virginia with a solid plurality of whites and high turnout and support from nonwhites — blacks and Latinos were 25 percent of the electorate and gave Obama 78.5 percent of their votes.

If Marist is correct, then the race in Virginia is well in Obama’s favor. His coalition remains intact, and all that’s left for the campaign is to boost support on the margins — especially among young whites, blacks and Latinos — and bring turnout as close as possible to 2008 levels. Moreover, because Obama and Kaine are running with identical coalitions, the fate of Tim Kaine depends heavily, if not exclusively, on how Obama performs. If Obama carries the state, then Tim Kaine will enter the Senate as Jim Webb’s replacement; if he doesn’t, we can look forward to another six years with George Allen, whose last act on the public stage was to casually target a Democratic campaign worker with an obscure racial slur.

One last observation: The key thing about Virginia is that it’s demographically similar to other states — such as Colorado — with a substantial portion of nonwhites and college-educated voters. If Obama is performing well in Virginia, then it suggests that he’s also performing well in those other states. Indeed, perhaps the key question for the Obama campaign is whether it can maintain or increase its performance among college-educated whites — as it has done in Virginia — while losing support among whites without college degrees. The most recent poll from The Washington Post — which shows wide dissatisfaction among middle-class whites — suggests that will be a tough hill to climb.