Now that Sen. Barack Obama is President-elect Obama, what will all the thousands of members of his vast, fabled grass-roots network do with the rest of their lives?

This weekend, at least, they're partying.

Across the country, Obama volunteers are hosting nearly 5,000 Obama-sanctioned "Change is Coming" house parties -- including about a dozen different events in the Pittsburgh region, from Sewickley to Canonsburg to Wilkinsburg -- even as Obama transition officials debate how best to harness the momentum created during the campaign.

So how does Mr. Obama build on his most precious asset: a sprawling, sophisticated high-tech field operation -- with 13 million e-mail addresses, tens of thousands of neighborhood "coordinators" and phone bank volunteers and hundreds of trained organizers -- to further his political agenda?

Last weekend, top Obama staffers in Chicago huddled behind closed doors to hash out that question, but no specific initiative has yet emerged. Instead, on a YouTube video posted on Mr. Obama's transition Web site, a tie-less David Plouffe -- a top adviser to the president-elect -- stood in front of the White House and urged supporters to attend or host the parties, to "talk with your colleagues, neighbors and friends about the best way to move this country forward, continue this movement [and] your ideas about what would be the best way to participate in your democracy."

Locally, that's already begun. Last Sunday, about 80 people braved freezing temperatures to attend a meeting in a Carnegie Mellon University auditorium for the unveiling of PittsburghHopes.org, a Web site for Obama volunteers -- and anyone else -- interested in "turning our hopes into action," said Kirby Krieger, a former Obama staffer based in the East End and one of the site's creators.

"Your voice was heard on Election Day," he told the group. "Now, with this Web site, we're seeking to put wings to the voice, and muscles on those wings."

Members of PittsburghHopes.org can join up to three "issue groups," and must commit to meeting regularly to present research, debate and set goals as the Obama administration prepares to take on the economy, health care, the Iraq war and other vexing problems.

"This is the beginning, not the end," added Saleem Khan, an Obama volunteer who, in his other life, is a professor of molecular genetics at the University of Pittsburgh School of Medicine, but who, since June of 2007, has been feverishly organizing volunteers in various East End neighborhoods -- dubbed "Dreamland" at one point by the campaign for its rich inventory of potential Obama supporters.

During a recent interview in a Point Breeze coffee shop, Dr. Khan could barely contain his enthusiasm about the experience.

"I met so many people from my neighborhood who I'd never seen before. Really wonderful people. There was so much bonding, so much energy, so much passion," he said. "We just have to think of ways to keep it going."

But how? Will volunteers focus their efforts on lobbying members of Congress about offshore drilling or after-school programs? Will they work to elect more Democrats to the U.S. House and Senate? Or should they focus on local political reform?

"We don't really know and we don't pretend to know and I don't think the Obama campaign pretends to know what they would like to have happen," said Mr. Krieger.

After Nov. 4th's ecstatic celebrations, the journey becomes bumpier from now on, since the coalition behind Mr. Obama by no means is united on all issues, noted J. Cherie Strachan, an assistant professor of political science at Central Michigan University.

"I think it's great what Obama did," she said, "but if it's just a personalized organization around a candidate, it can't be sustained after an election unless you turn it into something with an agenda other than electing the candidate, where people can come together on a regular basis," she said.

The last existing model of such an infrastructure, she said, can be found in black and evangelical communities, who have effectively mobilized their members over the years between elections.

Indeed, African-Americans who supported Mr. Obama "will continue to be highly involved through their churches," predicted Todd Shaw, a professor of political science at the University of South Carolina.

But many liberals and progressives aren't regular churchgoers, polls have repeatedly shown, and the Moose, Elks and other civic clubs, with their dwindling memberships, are no longer the glue binding American community life.

"After Sept. 11, all these people came out and said, I want to do something, I want to help, but they had no infrastructure to plug into since nobody belongs to these kinds of groups anymore," said Ms. Strachan.

Still, Mr. Obama's focus on neighborhood connections -- a strategy first successfully implemented by George W. Bush and Karl Rove -- was effective, said Andrew Heffner, 26, of Highland Park, a former youth pastor in Washington, Pa., who ran two Obama campaign offices in Homestead.

"There's so much of what President Bush did a great job of and Obama tried to learn from," he said. "To build things from neighbor to neighbor, to focus on small groups who have familiarity and natural connections with each other."

But what of residents in poor neighborhoods, who are too busy just trying to survive to join a volunteer group?

Mr. Shaw points to Harold Washington's election as Chicago's first black mayor in 1983, which unleashed a whole new wave of activism in that city -- and whose foot soldiers would eventually include Mr. Obama.

"You saw a lot of organizations spring up in the wake of that election, in community development and public housing," Mr. Shaw said.

Mr. Obama's "new" New Deal rebuilding America's roads and bridges could bring about the same result, but, he added, there needs to be an unprecedented effort to build multi-racial coalitions around specific issues, perhaps the toughest test of post-election grass-roots unity. On affirmative action, for example, Mr. Obama, a moderate on the issue, may get some pushback from an older generation of civil rights leaders, Mr. Shaw said.

"And how do you link urban blacks and suburbanites when that subject is, say, the environment? It's going to be tricky."

If Obama's supporters don't go to church as frequently as conservative voters, they do congregate at another temple -- the Internet. Mr. Obama famously used it to raise money and build support, but to keep his grass roots base healthy, "that technology must be used to facilitate face-to-face meetings," Ms. Strachan said.

That's exactly what Donna Baxter, of Bloomfield, an Obama volunteer and founder of Thesoulpitt.com -- aimed at Pittsburgh's black community -- did with her Web site.

During her time volunteering for Mr. Obama, she said, "my friends and I talked about how we could keep people connecting and participating afterwards."

So, she used her Web site to organize a bus trip to Mr. Obama's inauguration -- the Soul Pitt Charter for Change. "We're really going to come together on that trip, and I have a feeling when we get back we're going to be different, we're going to be more involved."

Other progressive organizations that worked for Mr. Obama's election are also examining how best to align their goals to Mr. Obama's -- which will require some finesse. MoveOn.org's Eli Paliser has said he hopes to put that organization's 4.3 million members to work for Mr. Obama, even if its political goals are to the left of the president-elect's.

Locally, Randy Shannon, who heads a chapter of Progressive Democrats for America in New Brighton, Butler County, hosted a breakfast yesterday for about 40 people, including Obama volunteers who support single-payer health care.

"It's a whole new ballgame now," said Mr. Shannon, whose group has its own Web site, Beavercountyblue.org, and has been working with the AFL-CIO on single-payer health care during the past few elections.

This time, "we wanted to bring in Obama volunteers to see if we could work together" -- even, as he acknowledged, it's not clear if the Obama administration will support a single-payer approach.

But Mr. Obama's most fervent supporters -- young people -- may fade back onto their college campuses, victims of burnout as much as anything.

Matthew McCabe, a senior at the University of Pittsburgh, worked 18-hour days as a paid Obama staff organizer in Scranton during the campaign, and is going back to school in January.

"I'm sure I'll stay involved, but a lot of that stuff is still being figured out," he said. "Sure, I miss the hectic, breakneck speed of the campaign, with a different level of excitement every day, but after the election I really needed to relax a little."

"People have to get back to their regular lives, we know that," said Mike Lambert, one of PittsburghHopes.org's creators, who is also hosting a house party today at his Squirrel Hill home.

But, he added, volunteers weren't really invited to come to the party, strictly speaking.

"If you hear what the Obama campaign has been saying all along, it's not an invitation, it's also a mandate," he said.

"They've been telling us, 'We need you. This is necessary. We cannot create the kind of change that you want without broad-based citizen support.' And unlike past elections, when afterwards it just went back to business ... now we have a government whose entire reason for being is due to grass-roots involvement. Obama has said repeatedly he can't do it alone, so we're taking him at his word."