For nearly five years, Sen. Hillary Rodham Clinton (D-N.Y.) has been a diligent lawmaker, introducing a blizzard of bills and amendments, forging relationships across party lines, establishing credentials on national security, and boosting her approval ratings at home by paying close attention to all regions of her state.

What she has lacked, according to some of her advisers and other Democrats, is a broader, more imaginative frame, a forward-looking national message that Democrats say they badly need in the wake of two demoralizing defeats at the hands of President Bush.

Now she is embarking on a project that could provide a new blueprint for the Democrats, and the foundation for her own possible presidential candidacy in 2008, as the leader of an initiative by the centrist Democratic Leadership Council (DLC) to create an agenda for the party. How she uses her new platform will demonstrate just how much she would take Democrats back to the 1990s or is prepared to lead them forward in a new direction.

Clinton's challenge will be to avoid offering the politics of restoration, whose appeal is built on an implicit return to the policies that guided her husband's administration. That would appeal to many Democrats who yearn for the successes of the 1990s, but the Clinton years carry considerable baggage for many independent and swing voters.

Some Democrats wonder whether Clinton can grapple with what ails the party today and come out of the experience as a candidate with an appeal and an identity distinct from her husband's administration -- one that fits far different times than existed when he was president.

"There's a feel of nostalgia creeping into her message that she has to be particularly sensitive to," said one veteran of presidential campaigns, who declined to be identified as publicly critical of the senator. The strategist added: "I think there's a sense of let's go back and revisit the Clinton model and that's the way to get elected. . . . I think it's going to be very hard for her to get out of the comfort zone of the Clinton administration."

Defenders say she can easily navigate from past to future. "I would quote her husband who often said -- and it's absolutely a truism -- that people vote the future, not the past," said Harold Ickes, who was White House deputy chief of staff in the Clinton administration. "Rhetorically she will invoke the halcyon days of the 1990s. The fact is she knows that people are concerned very much on the future and that she very much has to address that."

The Clinton brand is a powerful asset and a divisive force. As Bush showed when he ran for president in 2000, an attractive brand and past association with a presidency is not sufficient to win the White House. Bush's first presidential campaign may have been motivated by a desire to avenge the defeat of his father at the hands of Bill Clinton, but he did not run as the political twin of his father's administration or as the instrument to resurrect his father's agenda. He traded on the Bush name but did not allow it to restrict his vision.

How Sen. Clinton plans to deal with this, if she becomes a candidate in 2008, is far less clear. Bill Clinton presented himself as a New Democrat, Bush as a compassionate conservative. The senator has been a workaday legislator without a defining imprint of her own. In her DLC speech last week, she offered a description of an ideal America in 2020, which many in the audience regarded as an appealing vision, but it was not intended as the kind of hard-choices agenda that DLC leaders may envisage.

Clinton is the biggest celebrity in her party, but not the freshest face. If she hopes to be a bridge to the past and a gateway to the future, she may have benefited from listening to several potential 2008 rivals -- Iowa Gov. Tom Vilsack, Virginia Gov. Mark R. Warner and Sen. Evan Bayh (Ind.), who also spoke to the DLC conference. Each addressed more directly than Clinton questions Democrats will have to answer to win back independent voters and appeal more successfully to those in towns and exurban neighborhoods.

Warner noted, for instance, that Democrats have been talking about education, health care, the economy, fiscal responsibility and national security, but he said accelerating change in the world renders old ideas obsolete. "In a post-9/11, flat world, sometimes even the solutions that we offered in the 1990s aren't enough," he said. "Sometimes defending the same programs, thinking they're going to give us new results, makes no sense. We need leaders who can see farther down the road."

Clinton's work on the Armed Services Committee and her support for the invasion of Iraq when many rank-and-file Democrats opposed it show her determination to overcome the party's historic weakness on national security that plagued Sen. John F. Kerry (D-Mass.) when he ran against Bush last year. Her work on economic development issues crucial to Upstate New York has given her an understanding of how a Democrat can make inroads in red-state environments. Her admission of mistakes in trying to restructure the health care system in 1993 and 1994 shows she knows when to cut her losses.

The political benefits of Clinton's high-profile role with the DLC may seem obvious to the New York senator and the centrist organization. Clinton gains a platform from which to reinforce the moderate side of her political profile, and the DLC, struggling to maintain its influence inside the party, can trade on her star power to raise its profile and power.

But for the aspiring presidential candidate and the organization that helped launch her husband toward the White House more than a decade ago, the relationship may prove more difficult than first appearances suggest.

Her advisers say Clinton begins without an agenda of her own and with a goal of bringing all wings of the party together, which on issues from trade and Iraq to the role of religion in politics could prove extraordinarily difficult to achieve. "She begins with a clean slate," said Lorrie McHugh, Clinton's communications director.

The DLC risks being used by Clinton to blur differences between left and center within the Democratic Party. Clinton risks being caught in a political time warp that could make it more difficult for her to establish that she is not merely an extension of her husband's administration. And in taking on the assignment, Clinton has made it more difficult for her advisers to say she is focused only on winning reelection in 2006.

Gina Glantz, who managed Bill Bradley's campaign in 2000, said Clinton has an "extraordinary opportunity to set an agenda, a bold agenda, not amendments to legislation, but to really put forward a strong policy framework for the country."

If the new initiative results in a sharper, fresher, more future-oriented profile for a politician who already has been on the national stage for a decade and a half, the political benefits for the Democrats may be genuinely significant. If it produces lowest common denominator policies, vague statements of principle or intraparty warfare, then the DLC exercise may accomplish neither the DLC's nor Clinton's political aspirations.

Sen. Hillary Rodham Clinton is heading centrist Democrats' effort to draw up an agenda for the Democratic Party.