Sen. Lowell P. Weicker Jr., suddenly battling for his political life in a race that many thought just weeks ago would be a walkaway, is flooding Connecticut's airwaves with a series of ads striking back at his aggressive Democratic challenger. But Weicker's assault _ one he all but promised he would never launch _ has not yet brought the third-term Republican back to safety, according to a new poll that shows a virtual deadlock with a high number still undecided. Joseph I. Lieberman, 46, the state's soft-spoken Democratic attorney general who has matched the incumbent's spending dollar for dollar, trailed Weicker, 57, by one point _ 38-37 percent _ in a Hartford Courant poll released Tuesday. The survey, which had a margin of error of three percentage points, mirrored a poll released two weeks ago that showed the combatants with 39 percent each. That survey transformed the race, energizing Lieberman and putting Weicker on the defensive. The most telling information from the recent poll was the number of undecided voters _ 25 percent in the last full week of a well-publicized, statewide campaign. The undecided bloc was less than half of that at the same point in 1982 in Weicker's race against Democrat Toby Moffett, then a popular, four-term congressman. The Lieberman camp is euphoric over the poll results, which the Democratic challenger said was ``more than we originally thought possible.'' ``For a three-term incumbent, after 18 years, to be in trouble as deep as he is in a week before the election clearly shows the people of Connecticut believe it's time for a change,'' said Marla Romash, issues and communications director for Lieberman. But G. Donald Ferree, director of the poll, said the news is not all cheery for Lieberman. ``It's been a loss of support for Weicker rather than a conversion into the other camp,'' Ferree said. Each candidate blames the other's negative TV ads for the large number of undecided voters. They say the attack ads have distorted records and positions, confusing voters. Media consultant Carter Eskew began creating attack ads for Lieberman early on, including a series depicting Weicker as a bear who slept through votes while collecting thousands in speaking fees. But Weicker, who had a solid double-digit lead in polls through the summer, said he would resist the temptation to retaliate. ``I hope two things happen when the election votes are counted. No. 1, Lowell Weicker would have won, and No. 2, it will be the first nail in the coffin of the negative campaign that has become the vogue in America,'' Weicker said just days before the first poll showed his big lead had evaporated. A week later, he was on the air with his own series of ads denying Lieberman's charges and attacking the Democrat's state Senate attendance record and votes on taxes and drug sanctions. Weicker campaign manager Jay Malcynsky said the ads are clarifying the record. The media war is the chief contributor to the campaign's record-setting spending: Weicker plans to spend about $2.8 million and Lieberman anticipates spending $2.5 million. At that rate, the campaign will be the costliest in Connecticut political history. While the video sniping likely is adding to the confusion, the candidates' positions on issues _ strikingly similar on many and seemingly reversed in roles on others _ undoubtedly has added to voters' hesitation to back a candidate. Weicker, known as a maverick who bolts from the GOP rank-and-file on a range of social and foreign policy issues, has built one of the most successful political careers in Connecticut history by forging a delicate base of Republican voters, independents and Democrats swayed by his leadership role on civil rights and other social issues. This year he has won endorsements from the AFL-CIO, the National Organization for Women and a state nuclear freeze group. Although he has never lost a campaign in his quarter-century political career, a 3-2 Democratic voter advantage in the state makes Weicker's re-election bids inherently risky. ``You could run a blank face in Connecticut as a Democrat with a well-funded campaign and it puts the Republican in a position of having one foot in the grave and the other on a banana peel,'' Malcynsky said. Lieberman, in trying to punctuate the differences between himself and Weicker, has attacked the senator variously from the left and right, often sounding like the Republican facing a Democratic incumbent. He accuses Weicker of wanting to raise taxes, says he is too close to Cuban leader Fidel Castro and criticizes his opposition to a moment of silence in public schools. But Lieberman must walk a political tightrope, luring conservatives while keeping liberal Democrats in line. The Lieberman strategy is to hold Democrats, split the independent vote and capture conservative Republicans such as National Review Editor William F. Buckley Jr., who would rather have anybody else _ even a Democrat _ in office.