Democrats reacted with overwhelming skepticism yesterday to President Bush's pledge this week to work constructively with them on a second-term agenda, as the party begins an intense debate about whether to seek any common ground with Bush or to be implacable in opposition.

Many Democrats said the experience of the first term -- in which they perceive that Bush promised cooperation but governed in a highly partisan fashion -- has left them reluctant to cooperate with Bush unless he takes the first step by moderating his course on such issues as Social Security, judicial appointments and limiting lawsuits.

Other legislators and strategists, however, cautioned that being perceived as obstructionists is a perilous course. They pointed to Tuesday's defeat of Senate Minority Leader Thomas A. Daschle (D-S.D.) as an example of the cost to be paid in more conservative regions if Democrats become defined largely as anti-Bush in the president's second term.

"They make a profound mistake if they think we're demoralized," said Sen. Byron L. Dorgan (N.D.), a moderate Democrat whose reaction echoed the unyielding tone that generally prevailed among Democrats of all ideological stripes yesterday. "We're not going to roll over and play dead. . . . We had a setback, but we're as determined as ever to push our own agenda."

In a victory news conference Thursday, Bush bemoaned the combative atmosphere of Washington but also made it plain that he believes his conservative platform has been newly empowered by "the will of the people" and he is not planning to dilute it. In interviews, several Democrats said they heard gloating, not graciousness, in Bush's statement -- a reaction that suggests there may be little muting of the anger that dominated this year's presidential campaign, even with the election over.

"What I heard him say is 'If you already agree with me, I'll let you work with me,' " said John D. Podesta, a White House chief of staff for Bill Clinton and an important voice of the Democratic opposition as head of the Center for American Progress.

The choice facing Democrats -- accommodation or defiance -- is one facing any party that loses the White House, but it is especially acute this year. Even some legislators and strategists who have counseled pragmatic compromise over partisanship in the past say they see little reason to treat Bush's 51 percent victory as a mandate, or wipe clean the slate of past grievances. Different versions of this debate, Democrats said, will emerge in several near-term decisions, including the choice of who is to replace Democratic National Committee Chairman Terence R. McAuliffe.

Among the leading candidates, Democratic sources said, is Iowa Gov. Tom Vilsack. Other names in circulation, with varying degrees of seriousness, these sources said, are former Clinton aide Harold Ickes, a fierce partisan and skilled fundraiser; Donna Brazile, who ran Al Gore's presidential campaign in 2000; and Antonio Villaraigosa, former speaker of the California Assembly.

The job of DNC chairman is inevitably to rally partisan loyalists with an aggressive message. More delicate are the decisions of Democratic legislators, who may disagree with most of Bush's agenda but also must answer to voters at home who do not like partisan warfare in Washington.

"No capitulation," Robert L. Borosage, a liberal strategist and president of the Institute for America's Future, recommended at a news conference analyzing the reasons for Democrat John F. Kerry's defeat. "After waging the most divisive campaign possible, the president now claims he wants to reach out to all Americans. But in his first term, reaching out usually meant trying to enlist a couple Democrats to sign on to whatever policy proposal it is the president wanted to go forward with."

Matt Bennett, a Democratic strategist and aide to retired Gen. Wesley K. Clark's presidential campaign, said a strategy of reflexive and across-the-board combat was tried this year -- and proved not good enough for a majority.

"Democrats in the Senate are going to have to face some facts -- they can't filibuster everything," he said, noting that the GOP this week increased its majority in that chamber from 51 to 55 votes. While fights on important principles are inevitable, he said, "if being an opponent of what George Bush stands for worked, John Kerry would be president."

"If there was ever a time when we turned out our base, we did it this year -- it just was not enough," Bennett added. "Kerry's equivocation on the war was not the problem. It was not that he was too moderate. It's that, fairly or unfairly, he was not seen as having an alternative vision."

The new Senate minority leader, Harry M. Reid (D-Nev.), has not been known as a partisan warrior but said his party cannot be taken for granted if Republicans expect cooperation.

Sen. Richard J. Durbin (D-Ill.), who will be the new minority whip, told reporters that Democrats were not intimidated by the election results but would have to "be careful to pick our battles" in light of the lost seats. It is a "gross misrepresentation" to suggest that Daschle and others were defeated because of opposition to Bush legislation and nominations, he said.

Clinton weighed in yesterday on the Democrats' future, saying in a speech in New York City to the Urban Land Institute that Democrats should not be demoralized by Kerry's defeat and should resist the temptation to "sit around and whine," according to an Associated Press report.

While president and in the early part of Bush's term, Clinton regularly urged his party to try to seek constructive compromise whenever possible, on the belief that voters want results from their politicians. Now he believes that the party must be more aggressive in response to Bush's partisanship, according to Democrats who talk with him regularly.

Simon B. Rosenberg, president of the New Democratic Network, devoted to making the party more competitive, said he and many Democrats used to believe the key to success was to play down overt partisanship and seek common ground where possible. But many Democrats, he said, in the Bush era have concluded this approach is naive.

"What's changed in the Democratic psyche in the last two years is that we believe we have to oppose the Republicans because their agenda is not just different from ours but that it's dangerous," Rosenberg said. "We don't see ourselves arguing in a debating society between two alternative points of view. . . . We are fighting with a missionary zeal."

Sen.-elect John Thune (R-S.D.), who defeated Daschle, suggested that nothing would make him happier than for the Democrats to take this approach. "There's going to be a hesitancy by some of these [Democrats] to get too far out there" resisting Bush's agenda, he said, because they know from Daschle's experience, "if you do that, there's going to be a price."

John Breaux (La.), who is leaving the Senate, was among the Democrats who most frequently worked cooperatively with Bush in the first term. He urged Democrats to become more comfortable talking about faith and values.

"Running against the Republicans and God at the same time is almost an impossible task," Breaux said.

But the legislative agenda may make this repositioning hard. If Bush appoints social conservatives to the federal courts, including a potential Supreme Court opening, several Democrat legislators said they will have no choice but to resist aggressively. "If he does seek our advice before he makes the nominations, I think it will go a lot smoother," said Sen. Mark Pryor (D-Ark.).

Staff writer Charles Babington contributed to this report.

DNC Chairman Terence R. McAuliffe at this year's convention. McAuliffe may be replaced by Iowa Gov. Tom Vilsack.