WASHINGTON — Top fundraisers for Sens. Hillary Rodham Clinton and Barack Obama have begun private talks aimed at merging the two candidates' teams, not waiting for the Democratic nominating process to end before they start preparations for a hard-fought fall campaign.

Despite Obama's apparently insurmountable lead in delegates needed to claim the nomination, aides to both candidates are resigned to the idea that the Democratic contest will continue at least through June 3, when Montana and South Dakota will cast the final votes of the primary season.

But in gatherings around Washington and in planning sessions for party unity events in New York and Boston in coming weeks, fundraisers and surrogates from both camps are discussing how they can put aside the vitriol of the past 18 months and move forward to ensure that the eventual nominee has the resources to defeat Sen. John McCain, R-Ariz., in November.

Mark Aronchick, a Philadelphia lawyer who has raised more than $1 million for Clinton's bid, said that while her supporters have not given up, they recognize the need to start preparing for the general election.

"Only if we do this right, and see this through in the right way, will there be a chance for a full, rapid and largely complete unification of the party," Aronchick said.

Aronchick was one of about 35 Clinton and Obama insiders who attended a dinner here last week aimed at what he characterized as helping the two sides "grope towards unity."

The gathering, held at the Ritz-Carlton residence of Jim Johnson and Maxine Isaacs, was a fundraiser for the Democratic National Committee at which former Treasury Secretary Robert Rubin was honored. But the guests were well aware of the symbolism as they sipped cocktails and admired the views of the Potomac River. The event honoring a prominent Clinton supporter was held at the home of an Obama backer and co-hosted by another, former Sen. Thomas Daschle of South Dakota.

"The people there had all picked sides," one attendee said. "There was a sense that there is an obligation to lead by example."

While there was little outright talk of how the primary campaign would end, guests confirmed that DNC Chairman Howard Dean set the tone with a speech in which he emphasized that despite the protracted nomination fight, he is already instituting a plan to combat McCain.

The message was clear, according to one attendee, who said, "You don't go anywhere anymore where there isn't a sense that this is over and this is about how people behave over the next month."

Even with the work in top levels of the party to broker a detente between Obama and Clinton donors, both sides acknowledge there is still much to be done.

Top fundraisers have invested not only their time and money but also their emotions in the primary battle. Major financial backers say the tensions have been particularly acute in recent weeks as frustrations have mounted in both camps.

Aronchick said that in his own discussions, he emphasized the need for Obama to stop describing Clinton and her backers as representing the politics of the past.

"They need to understand how corrosive that has been among her supporters," Aronchick said. "For this to work, they need to correct any impression that he thinks we represent the old ways of doing things or Washington Beltway ways of doing things."

One top fundraiser for Obama, a veteran of several presidential campaigns who spoke about the private discussions on the condition of anonymity, said there are sensitivities among many of Obama's supporters as well. The fundraiser said there is a high level of resentment that Clinton has continued to campaign, even though her chances of securing the nomination are remote. Many are unhappy about having to make room for members of Clinton's finance team, who had "picked the wrong candidate."

Kirk Dornbush, a member of the Obama national finance team in Georgia, said that while there is no formal effort by the Obama campaign to recruit Clinton counterparts, "many of us have friendships with Clinton donors that predate the 2008 campaign and will last long after this race is over. Given this reality, it should not be surprising that we have received phone calls in the last few weeks" from individuals interested in crossing over.

Another major Obama fundraiser, granted anonymity to speak candidly, said that while no organized recruitment campaign was under way, "we have picked off some local people and are reaching out to the Clinton people we know individually."

That outreach has been complicated by leading voices in the Clinton campaign having made clear that any defection at this point would be regarded as a betrayal of the former first couple. "Some (Clinton) people have said, 'If you publicly defect, that's the end of our relationship,' " the Obama fundraiser said.