Bridgewater and Lee have sparred constantly since ousting incumbent Republican Robert Bennett in last month's state Republican convention.
Both candidates played on conservative anger over federal bailouts and President Obama's recently passed health care reform legislation. Bennett has held the Senate seat since 1993.
Both candidates campaigned as conservative Washington outsiders, with Lee focusing on Bridgewater's business dealings, and Bridgewater reminding voters that Lee is a Washington D.C.-based lawyer.
By midnight, Lee led Bridgewater by two points with 98% of precincts reporting. Lee led Bridgewater by nearly 4,000 votes.
Just after 11:00 p.m., Bridgewater conceded to Lee at his campaign headquarters.
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