Not long after the late Pittsburgh Mayor Bob O'Connor checked himself into a hospital, he worried that news of his cancer diagnosis might distract from the hype and excitement surrounding this summer's baseball All-Star Game, wanting nothing to interfere with a rare national marketing opportunity for Pittsburgh.

Even from a hospital bed, battling for his life, Mr. O'Connor understood the fragility of civic momentum -- how hard it is to gain and how easy it is to lose.

"I am very optimistic we can keep this momentum going," said Allegheny County Chief Executive Dan Onorato, now the region's best-known and most powerful politician. Doing so would provide "the best tribute to Mayor O'Connor," he added. "Let's keep it moving."

The push to build on the momentum of Mr. O'Connor's aborted term is already under way. Corey O'Connor, the late mayor's son, launched the Steelers home opener Thursday night by waving a ceremonial Terrible Towel. Then, on Friday, several economic development groups started a marketing campaign designed to build momentum for the city's 250th anniversary in 2008. The kickoff event, at the Senator John Heinz Pittsburgh Regional History Center, originally was scheduled for earlier in the week, but the organizers pushed it back, to the day after Mr. O'Connor's funeral.

The timing was no accident, Mr. Onorato said.

"Bob would want to see everything continue," he said.

It is "important," said Oxford Development Co. President David Matter, to show that "things are under control" and that "we are going to continue to make progress and not lose momentum." Mr. Matter was a top aide to the late Mayor Richard Caliguiri, who also died in office.

Mr. Matter argued that Mr. O'Connor "started the ball rolling down the hill. I think there is every reason to believe it will keep rolling and pick up speed as it goes along as long as people continue to work at it."

Boosters point to several signs of progress -- new leadership at the Pittsburgh Public Schools, an array of Downtown development projects and a renewed cooperation between city, county and state -- that can continue without the presence of Mr. O'Connor. Mr. Onorato pledges that the city-county relationship will be just as strong, citing a closeness with the Ravenstahl family and with the mayor himself. "Luke and I have known each other our entire lives," he said.

While the loss of Mr. O'Connor "will be hard for all of us, and the region, to overcome," said Max King, president of The Heinz Endowments, the area's second-largest philanthropy, "we have a couple of things to rely upon. First, this region is possessed of the same straight-from-the-shoulder, hard-driving, hard-working energy that characterized Bob's leadership; and, second, there are a host of other good things going on in our town just now, including the leadership of Dan Onorato at the county, Mark Roosevelt in the schools and Jim Rohr at the Allegheny Conference and the Pittsburgh Cultural Trust."

Mr. Rohr, chairman and chief executive officer of Pittsburgh's largest bank, PNC Financial Services Group, promises not to slow things down on his end. His company, after all, is building a new office and condominium complex along Fifth Avenue -- the cornerstone of efforts to revitalize the ragtag Fifth and Forbes retail district. Also, Mr. Rohr took over in January as chair of the Allegheny Conference on Community Development. At the same time, the banking executive chairs the Pittsburgh Cultural Trust, which recently announced plans for the biggest Downtown housing development in the city's history.

"Bob's leadership will be missed," Mr. Rohr said, "but I am confident that the public and private sectors can maintain the momentum he established to achieve the greatness he saw in our city."

Not everyone believes the transition will be that smooth, however. Former Allegheny County Chief Executive James Roddey worries about the limited experience of Mr. Ravenstahl and his ability to deal with structural financial problems the city still faces.

"What will be missed is a great deal of leadership," Mr. Roddey said.

"I don't think the city has turned the corner yet. We are still losing population ... so while I think Bob brought a new spirit and new attitude and everybody felt, wow, we had a leader who was resolved to do something, we really have never gotten to those serious problems."

The period following Mr. O'Connor death "can't help but be disruptive and delaying in many cases," said Cliff Shannon, president of the SMC Business Councils and a former chief of staff to the late U.S. Sen. John Heinz, who also died while in office.

"To what extent we will find out."

Businesses with improvement or expansion projects that need City Hall approval are feeling a lot of uncertainty right now, Mr. Shannon said, not knowing if the person they dealt with today "will be the right person tomorrow." In a few weeks, Mr. Shannon said, "anybody with money riding will start to squeal."

"If you are a business person, taxes are still too damn high and it looks a lot more attractive to go somewhere else to start your business or to expand your business," Mr. Shannon added. "O'Connor didn't have a chance to address that substantially. People who work in the city and own and run businesses in the city are anxious to have some attention to all of that."