With her warm-and-fuzzy "listening tour" a thing of the past, Hillary Rodham Clinton has shifted her Senate campaign into battle mode and begun staking out a liberal agenda that sharply distinguishes her from her likely Republican rival.

Facing a formidable opponent in the socially moderate New York mayor, Rudolph W. Giuliani, Clinton has begun to portray him as a creature of a conservative nationRepublican Party that is not in sync with the New York political environment. At the same time, she has moved more aggressively to inoculate herself from potential criticism, stressing her interest, for instance, in incremental change in the health care system rather than the wholesale change she pursued so unsuccessfully in the early years of the Clinton administration.

In recent speeches, news conferences and campaign statements, the firy has gone after Giuliani for supporting a massive--and, she says, irresponsible--tax cut, oppos an increase in the minimum wage and rejecting the nuclear test ban treaty. She has positioned much of her most recent criticism of Giuliani within a broader condemnation of Republicanism, from the presidency of Ronald Reagan to the present, which she said would hurt average New Yorkers.

"Whoever does represent the working people of New York . . . has to be willing to stand against any effort to take a U-turn to the past," Clinton said Wednesday in Rochester, before the New York State Public Employees Federation, in one of many allusions to Giuliani without naming him directly.

"There are some who believe that we should go back to the era of trickle-down, supply-side economics," she said in an oblique reference to a Giuliani speech a few weeks ago in which he praised Reagan's policies and the Reagan legacy.

To Clinton's campaign advisers, this more issues-driven phase of the campaign is unfolding because Giuliani keeps handing them ammunition, in their view, by aligning himself with the conservatism of the national Republican leadership. Although the state has its first GOP governor in two decades, the Clinton campaign is trying to suggest that Republicanism and New York are mutually exclusive.

The stepped-up effort to demonize Giuliani also is fueled by the knowledge that he is a Republican who--at least during previous campaigns--was moderate enough to twice win the mayoralty of the overwhelmingly liberal and Democratic city of New York. Clinton's campaign fears he could win some undecided Democratic votes, especially in upstate New York.

These dynamics are unfolding on a political playing field where Clinton has had some difficulty gaining traction. After the July announcement of her exploratory Senate campaign, her advisers had wanted her to steer clear of specific issues while New Yorkers became accustomed to her presence. This would help defuse the "carpetbagger" accusation that has been flung at her because she has never lived or worked in the state.

Despite her "listening tour" and intense fund-raising all over the state, Clinton has struggled to keep up with Giuliani in the polls, with her popularity remaining in the low 40 percent range all summer.

"Clearly, celebrity status did not win out over carpetbagger in the first round, so what she needs to do is what Democrats often do in New York, which is to run against Republican national issues," said Lee M. Miringoff of the Poughkeepsie-based Marist Institute for Public Opinion.

The downside to this strategy is that it leaves Clinton vulnerable to her original albatross: her outsider status, said Fred Siegel, an analyst and history professor at the Cooper Union for the Advancement of Science and Art in New York.

"If she plays 'national Democrat' against 'national Republican,' it allows him to play New Yorker versus Washington," Siegel said. "This also presents her as an outside candidate."

Although neither she nor Giuliani has officially announced, Clinton said yesterday at a birthday fund-raiser that she is "honored to be in this race, looking to succeed someone whom I admire," veteran Democrat Daniel Patrick Moynihan, who is retiring. Analysts predict that the race will be tight and bitterly fought between two politicians so well known that they have already edged out potential challengers in their parties.

Both are accomplished politicians, but they each also bear the dubious distinction of some remarkably high negative ratings--39 percent for both, according to a Marist poll released earlier this month. That same poll put them virtually neck and neck: Giuliani at 46 and Clinton at 43. A more recent poll, released this week by Zogby International, put Giuliani at 51 percent and Clinton at 40.

Despite her star quality--or perhaps as a byproduct--Clinton is beset by negative perceptions in part because of the aggressive role she played in the Clinton administration's far-reaching health care agenda. Her failed effort to sell Congress on the plan five years ago tarnished her reputation and provided fodder for critics who see her as rigid and ideological.

But as part of her methodical uphill battle here, Clinton has sought to tap into broad public insecurities about the cost of health care as she recasts her views and attempts to build new momentum around them.

To defuse criticism about her past health care reform agenda, she addresses it head-on. She routinely tells audiences that people might be wondering why she's even talking about health care at all, considering the fiasco of the past. She answers her own rhetorical question by saying it's an issue she has cared about and worked on for many years.

In numerous speeches, she has explained that her views today--which she describes as the "school of small steps"--represent an evolution from her more ambitious plans of the past. Among the key issues in her still-evolving health care platform are a strong "patients bill of rights," including the right to sue health maintenance organizations; expanded prescription drug benefits for Medicare recipients; and the general solvency of Medicare and Social Security in the future.

"I am not here today to offer a sweeping plan that will solve every problem in our health care system," she told a recent statewide conference of hospital administrators. Still, she made clear that while her methods in the past were faulty, her goal remains the same.

"We have to remain committed to the ultimate goal of providing health insurance--quality, affordable health insurance--to everyone in our country," she said.

Health care is a big concern of New York voters, said Maurice Carroll of the Quinnipiac College Polling Institute. "She's not identified with the positive side of it," he said. Therefore, he added, "for her to start staking the thing out makes . . . a lot of sense."