SPRINGDALE, Pa. -- Three-term incumbent U.S. Rep. Melissa Hart was tossed by voters who preferred a political novice on Tuesday.

Hart, a Republican who has served three terms in her North Hills district, lost to Democrat Jason Altmire, a health-care executive in Springdale.

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Slideshow: Commitment 2006: The Winners And Losers

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Hart initially refused to concede the close race after she said official numbers from Beaver County were not reported, and sent lawyers to the county courthouse to confirm. Later, after hearing word from election officials, she did concede.

Altmire finished with 52 percent of the vote, compared to Hart's 48 percent.

Hart was clearly upset, feeling that ruthless campaigning had influenced the vote.

"In retrospect, I had everyone in (Washington) D.C. say, you need to cut his legs off," said Hart, who had called for an end to negative television ads from outside groups last week. "But you know what? You don't need to cut his legs off. He clearly did that his entire campaign. He's new at this. I hope that he doesn't do it the next time."

Altmire acknowledged the effectiveness of the TV spots.

"I don't want to talk about whether it got negative, but those ads pushed me over the top. There's no question about that," Altmire said. "I always felt that if we got close at the end, the national people would take a look and realize that we could win, and that's exactly what happened."