Former vice president Al Gore is sparking a sharp debate within the Democratic Party as he begins to emerge from self-imposed exile, underscoring the obstacles he will face if he decides to seek the presidency again in 2004.

Gore's closest confidants say he has made no decision about whether to seek a rematch against President Bush and has the luxury of not having to do so for many months. But as Gore returns from a summer in Europe, Democratic activists and potential rivals assume he is preparing plans for a gradual reentry this fall, with an eye toward another presidential bid.

If he does, they say, he will face bitterness from some Democrats over his performance in the 2000 campaign, stiff opposition for the Democratic nomination in 2004 and the defection of some advisers and fundraisers to other campaigns.

"We have people in the party who believe he blew it," a former top adviser said. "There are hard-core Democratic donors and operatives who believe that Al Gore was not up for the contest."

Democratic strategists and Gore loyalists agree that he must repair his relationship with former president Bill Clinton, which one described as "a bad problem." He also needs to reaffirm his ties to the party's most important constituencies, including organized labor and minorities.

Gore's allies say the inside talk among Democrats overestimates the obstacles he faces. Gore, they say, enjoys substantial advantages over any of the others who might seek the Democratic nomination, including goodwill among many Democratic voters who believed he was robbed of the presidency, strength in early polls against potential rivals, including Bush, and the confidence from having run before.

"I agree with his decision to take some time away and gather his thoughts and give the new administration a period of time," said Carter Eskew, a Gore friend and strategist. "My feeling to everyone is, take a deep breath, relax."

Still, Gore's advisers acknowledge that another bid for the presidency would be far more difficult than the last. He may be able to wait longer than other candidates, an adviser said, "but that doesn't mean he's not going to have to go out and work for it. He will have to work harder than the last time."

Whether Democratic voters believe Gore deserves another chance may depend on the impressions Gore makes when he begins to speak out this fall. A top adviser from his previous campaign said that "the most important thing" Gore must figure out before he fully returns to political life is "who he is," the same issue that dogged him during the last campaign.

"Whoever he emerges as in the fall or the winter, he's got to be consistent over the next couple of years," said this Democratic strategist.

Gore's return to the political -- though not the public -- arena begins this week. He and former Tennessee governor Lamar Alexander (R) hosted a bipartisan workshop on politics yesterday in Nashville. Beginning today, Gore will host a private training academy for about two dozen young Democrats who will then go to work in Democratic campaigns and state parties -- and perhaps another Gore campaign.

But aides sought to dampen discussion of whether that means Gore will run again. "Vice President Gore is on his way back to Tennessee and getting back to work," said Peter Knight, who is one of a few people helping Gore plan his next moves. "All discussion about who's going to run for anything is absolutely premature, and what is important is his lifelong commitment to the issues of importance to Americans and our families, and I expect you will be hearing a lot from him on that."

The next few days will be like old times in Nashville, where Gore's presidential campaign was located. There will be a Sunday night barbecue with the former candidate and long days spent talking about the nuts and bolts of politics. The faculty includes senior strategists from Gore's 2000 campaign, plus Gore himself.

Despite criticism from some Democrats who said he should have been attacking Bush earlier, Gore has preferred a gradual emergence. He spent the summer in Europe (where he grew a beard that he has not shed), vacationing with his family and working on a book with his wife, Tipper. (Democratic sources say Tipper Gore prefers that her husband not run again.) While there, he also made several speeches, his principal source of income now that he is out of office for the first time in a quarter century.

This fall he will resume teaching at Middle Tennessee State University and Fisk University. He has set up an office in Tennessee and plans to spend a day or two a week in the state, where he will tend to political fence-mending after having lost his home state to Bush.

Gore also recently leased office space in suburban Virginia for a new political action committee that he will formally launch this fall. The PAC will pay for his political travels this year and next and make contributions to other Democrats. Gore has agreed to campaign for New Jersey Democratic gubernatorial candidate James McGreevey, the first of many pledges Gore has made to campaign for Democrats.

Democratic National Committee Chairman Terence McAuliffe said he hopes to sign up Gore to raise money for the party but has yet to receive a commitment.

Aides said Gore has not told them when he plans to begin speaking out on issues. They know he will be a magnet for Republican criticism the moment he tries. But they also say Bush has accumulated a record on taxes, the budget, the environment and foreign policy that they believe will give Gore an opening.

Rebuilding his relationship with Clinton also looms as a necessary piece of unfinished business. Clinton's determination to remain politically active casts a shadow over Gore. "He's trying to suck the political oxygen out of the air," a Gore adviser said. For now, Clinton's prominence keeps alive talk of the bitterness that developed during the last campaign between the two men and their respective teams of advisers.

Other potential presidential candidates have visited Clinton this year to seek his advice, but ever since a contentious Oval Office meeting late last year, Clinton and Gore have had little contact. "The first step in healing the relationship is to yell at one another, so step one has been done," a Gore adviser joked.

Gore and Clinton did speak privately at the funeral for former Massachusetts representative Joe Moakley (D) and Gore later told a friend, "I had a very good conversation with the president."

Another potential contender for the 2004 Democratic nomination is Sen. Joseph I. Lieberman (D-Conn.), Gore's running mate last year, but Lieberman has said he will not run if Gore does.

Democrats have talked privately about an arrangement in which Gore and Lieberman would run as a ticket, even during the Democratic primaries, but there are conflicting accounts of whether that has been discussed seriously. Lieberman supporters do not like the idea, but a Gore adviser, saying he knew of no such agreement, said, "That is something I find personally exciting. Politically I think it's powerful."

Even if Lieberman didn't run against Gore, plenty of other Democrats would. A senior Democrat listed almost a dozen potential candidates for the 2004 nomination, including House Minority Leader Richard A. Gephardt (Mo.); Senate Majority Leader Thomas A. Daschle (S.D.); Sens. John F. Kerry (Mass.), John Edwards (N.C.) and Joseph R. Biden Jr. (Del.); and California Gov. Gray Davis.

Gephardt in particular could fracture the strong support Gore had in 2000 from organized labor and would make a victory in the Iowa caucuses more difficult. Democratic strategists say Kerry's Massachusetts base could make him a strong candidate in New Hampshire. There also is talk that the DNC might change the primary calendar for 2004 by moving a southern state into the early weeks of the process, a change that would be seen as helpful to Edwards.

Although the other potential candidates could pose a challenge, early polls show Gore with an edge. A recent CNN/USA Today/Gallup poll showed that 65 percent of Democrats surveyed would like to see Gore run again. The poll indicated that Gore is the leading choice of Democrats for the 2004 nomination, favored by about one-third of those surveyed. Sen. Hillary Rodham Clinton (N.Y.), who has said she will not run, was second. But only 9 percent identified Gore as the current leader of the Democratic Party (no other Democrat was higher), with 59 percent saying either "no one" or "no opinion."

In a head-to-head matchup, Gore and Bush were tied at 48 percent, showing that despite Gore's seven months of silence, the electorate remains as divided as it was in November.

Still, Gore faces potential difficulty with donors, some of whom are angry about his loss and believe they have not been adequately "stroked," as a former Gore aide put it, since the election, or are upset by Gore's breach with Clinton.

Another fundraiser said, "People were disappointed that the campaign was lost, but then again, time heals a lot of wounds." As for the danger that other candidates will lure Gore donors as he ponders whether to get into the race, this fundraiser said, "I think that 95 percent of the fundraising base will stay somewhat uncommitted until this field sort of presents itself. It's not much of a risk."

Others were harsher. "People are mad at him because he never should have been in this position," one said. "People that I talk to say he had his moment in the sun and it's gone."

William Daley, who chaired Gore's 2000 campaign, said the former vice president should decide for himself how and when to reemerge fully, arguing that there is little to be lost by continuing to take it slowly.

"I've always felt that longer is better for him," Daley said. "He's got name recognition. No one is going to get ahead of him in the polls. He's got the most contacts. He's done it three times and nobody has as much experience. When he does come out, I think there will be interest in him. The longer you wait, the more interest there may be."

Al Gore, left, and former Tennessee governor Lamar Alexander answer questions at a bipartisan workshop for young people interested in politics.