Clinton's numbers had been stalled for most of this year, but some polls had detected a bounce for her after their first debate, on Sept. 13, during which Lazio strode across the stage, thrust a piece of paper at her and demanded she sign a pledge to ban soft money from the campaign.

Some voters, especially women, were offended by what Clinton spokesman Howard Wolfson called a "menacing" approach.

According to the poll issued Wednesday by the Quinnipiac University Polling Institute, Lazio trailed among likely voters with 43 percent. A Sept. 12 poll from the institute had Clinton leading the congressman from Long Island 49 percent to 44 percent.

In recent weeks, the Lazio campaign has made much of Clinton's failure to hit 50 percent in the polls. His campaign downplayed the new poll Wednesday, with spokesman Dan McLagan noting that statistically, "there's no change from the last Quinnipiac poll."

Lazio, professing a lack of concern as he campaigned in upstate New York, did call himself "the underdog in this race" -- a term he hasn't used in weeks.

Quinnipiac's telephone poll of 889 likely voters, conducted Sept. 20-25, has a margin of error of plus or minus 3 percentage points.

"We know this race is going to be close, but it's nice to hit the big five-oh," Wolfson said.

While 38 percent of voters said they viewed the first lady unfavorably -- no real change from past polls -- Lazio's unfavorable rating reached 29 percent after heavy anti-Lazio TV advertising from the Clinton campaign and the congressman's aggressive performance during the debate.

"I was for her already before the debate and it made me feel for her even more," said Fran Goodstein of Yonkers as she shopped Thursday at the Galleria Mall in White Plains.

But Serena Maglio of suburban Greenburgh said: "He thought he had to do what he did and you can't tell me it was so terrible."

In a discouraging note for Lazio, the Quinnipiac poll found the race extremely close in traditionally more conservative upstate New York, with Lazio at 46 percent and Clinton at 44 percent.

In the New York City suburbs, Lazio led 53 percent to 40 percent, but in the heavily Democratic city itself, Clinton was ahead 67 percent to 39 percent.

Last week, a Marist College poll had the two tied at 48 percent each among likely voters. And a New York Times/CBS News poll had Clinton leading 48 percent to 39 percent among likely voters.