Democrat Tim Kaine edged Republican George Allen on Tuesday night to capture Virginia's Senate seat, a critical win that helped his party keep control of the upper chamber for another two years.

Allen conceded the race about 10:55 p.m. to supporters huddled up in Richmond as Kaine's small but sizeable lead continued to grow. With 95 percent of precincts reporting, Kaine led with 51.5 percent of the vote to Allen's 48.3 percent.

Kaine, also in Richmond, was joined by his wife, Anne Holton, and thanked her for his victory.

"When I got into this race I was 7 for 7 [in elections]," Kaine said. "When I knew I had her help, I knew I couldn't lose."

Kaine pledged on the campaign trail to be a champion of bipartisanship and an antidote to a poisonous atmosphere in Washington. He modeled himself after political mentor and friend Sen. Mark Warner, who has a record of working across the aisle. Kaine's appeal among some moderate Republicans allowed him to outpace President Obama in Virginia by 2 percentage points.

Kaine, who served as Democratic National Committee chairman from 2009 to 2010 and was Obama's handpicked candidate, is the latest in a long line of former Virginia governors to move on to higher office.

The son of a Kansas ironworker, Kaine is a well-known commodity throughout the Old Dominion for his two decades in both local and state politics. After serving as a councilman and mayor of the capital, Richmond, throughout the 1990s, he moved on to statewide politics. In 2001, he successfully ran for lieutenant governor on the same ticket as Democrat Mark Warner, and then succeeded Warner as governor.

In besting Allen, Kaine allowed Democrats to hold on to the seat soon to be vacated by retiring Sen. Jim Webb, D-Va.. His victory was a major piece in helping his party hold onto their Senate majority.

For Allen, the close loss ends his attempt at a political comeback and his chance to win back the Senate seat he lost to Webb in 2006 by fewer than 10,000 votes. But Allen, also a former governor, faced headwinds from the start and was ultimately unable to overcome "an underwhelming showing" in the state by Republican presidential nominee Mitt Romney.

Allen, standing with his family in Richmond, asked his supporters to hold their heads high while admitting defeat.

"We haven't succeeded, my friends," Allen said.

The race was one of the most closely watched and attracted an infusion of money from outside political groups who flooded the airwaves with negative ads. The race was ultimately the most expensive Senate contest in the country.