Updated

Republican Sen. George Allen is slightly ahead of Democratic challenger Jim Webb in a closely watched race that could determine whether the GOP retains control of the Senate, according to a poll published Monday.

A statewide survey by Mason-Dixon Polling & Research Inc. showed that 47 percent supported Allen while 43 percent favored Webb, a former Republican and first-time candidate. Two percent supported independent Gail Parker, and 8 percent were undecided.

The results, published on the Web sites of several Virginia newspapers, are based on telephone interviews conducted Oct. 17-19 with 625 registered voters statewide.

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Allen's tenuous advantage is equal to the poll's margin of error of plus or minus 4 percentage points. His campaign was optimistic.

"We know what we have to do and we know how to get there, and when people vote issues and issue differences, they're going to vote for George Allen," said Christopher J. LaCivita, a longtime Allen adviser.

Allen held a 16-point lead over Webb in July but saw it vanish after weeks of damaging developments beginning Aug. 11, when he called a young man of Indian descent "macaca," an obscure racial slur.

Webb's chief strategist, Steve Jarding, said he is confident the Democrat remains on track.

"We feel very good about these numbers and the numbers in other recent polls, including our own, that show Jim moving up while Allen is moving down," Jarding said. "These numbers show Allen has hit his ceiling."