Pittsburgh area politicians and community leaders cited Mayor Bob O'Connor's energy and fighting spirit as qualities that will serve him well as he battles cancer.

All expressed shock and offered prayers to the mayor and his family after learning details this afternoon about the diagnosis of primary central nervous system lymphoma.

But nearly all also mentioned Mr. O'Connor's energy and enthusiasm.

Allegheny County Chief Executive Dan Onorato said, "Our thoughts and prayers are with Mayor O'Connor, his family and staff. I know the mayor will face this challenge with the same energy and determination that have come to define him."

Mr. Onorato said he was told of the mayor's cancer by Dennis Regan, the city's director of intergovernmental relations, about half an hour before the news broke. He said Mr. Regan and other staff members told him that Mr. O'Connor would not be incaptitated by the illness or treatment.

"Everybody knows Bob O'Connor is a fighter. He's got the best medical team he could have and we're wishing him well."

Mr. Onorato said he plans to continue to meet weekly with the mayor, as they have done since Mr. O'Connor took office, to discuss city and county business.

"I don't see this changing anything, the two of us meeting. The city and the county will continue to work closely together."

Gov. Ed Rendell noted that the news comes as Mayor O'Connor's city is hosting Major League Baseball's All-Star Game tomorrow. The mayor has been sprucing up the town in advance but will not be able to attend.

"Bob O'Connor seems like such an indestructible guy, always on the go," said the governor, who was in Pittsburgh for the events surrounding the game.

"I'm sure his message to the region and to the people of Pittsburgh would be, 'Be proud and enjoy the game.' "

Mr. Rendell then offered the mayor his own message: "Take it easy. Don't worry about us. Don't worry about the city. The city looks great. The city is at one of the high points in its revitalization."

He promised that the state would provide help for city government if necessary, but he expressed confidence in the abilities of Mr. O'Connor's staff. He also suggested that the mayor would follow the example of U.S. Sen. Arlen Specter, who continued to work last year even as he underwent chemotherapy for Hodgkin's disease.

Marlee Myers, managing partner of the Pittsburgh office of the Morgan Lewis law firm, said Mr. O'Connor has been "so enthusiastic about the job -- I would hope that the enthusiasm and obvious energy and vigor -- I hope that it'll carry him through along with the great treatment I'm sure he'll get."

On June 28, while inspecting new routes students may have to walk next school year, Pittsburgh Public Schools Superintendent Mark Roosevelt covered ground at a considerably faster clip than Mr. O'Connor.

That's because Mr. O'Connor repeatedly stopped to shake hands with pedestrians and motorists and even ducked into an automotive shop to say hello while Mr. Roosevelt waited for him. No detail was too minor for Mr. O'Connor, who thanked drivers for obeying the speed limit, ordered a storm-water grate repaired and mused about the need for crosswalks at certain intersections.

Mr. Roosevelt, a former Massachusetts lawmaker and unsuccessful gubernatorial candidate in that state, didn't mind Mr. O'Connor's tarrying that day, and today he said he has enjoyed watching Mr. O'Connor enjoy being mayor.

"His enthusiasm for his work, his enthusiasm for Pittsburgh, are contagious and very important, and the fact that he loves the job, I think, is very important. I just hope very much that he gets to keep doing it," Mr. Roosevelt said.

Mr. Roosevelt said Mr. O'Connor's gung-ho attitude should help him now: "One thing I do understand is that attitude matters in these things."

City Councilman Jim Motznik of Brookline was vacationing in Myrtle Beach, S.C., when his office contacted him and read him the statement from the mayor's office.

"I'm shocked," Mr. Motznik said. "Bob is such a great guy and the residents of Pittsburgh finally have a mayor they can relate to. Bob gives the residents of the City of Pittsburgh hope they haven't had before.

"I'm sure once the treatments start Bob will be able to operate the city. I'm sure he'll end up being one of the best mayors we've had."

Some community leaders already have been giving the mayor high marks.

Every Saturday morning after buying a Starbucks coffee in his Squirrel Hill neighborhood, Mr. O'Connor drives to East Liberty to shoot the breeze at Vento's Pizza on Highland Avenue and run his car through a car wash. He often leads walking tours in the area.

"He gets his face out there," said Rob Stephany, director of commercial real estate development for East Liberty Development, Inc.

Mr. Stephany said the mayor's tenure has given the neighborhood the sense that "people in the city are oriented to the changes that are happening [in East Liberty] and are trying to help.

"If his personality is any indication, he won't let this get him down."

Ed Brandt, director of the Brightwood Civic Group, said the mayor's "Redd Up" campaign has built a support group in the Marshall-Shadeland neighborhood that grows larger with every abandoned car that's towed and every decrepit building that's boarded up.

"At least people say, 'He's out there and he's trying,' " Mr. Brandt said. "People are very appreciative that he has dug in there on the neighborhood issues."

Aggie Brose, a long-time acquaintance who is deputy director of Bloomfield-Garfield Corp., said her office sent the mayor a fruit basket today after he had been released from UPMC Shadyside, where he was diagnosed with a duodenal ulcer before today's cancer diagnosis.

"Bob O'Connor is a very very good person," said Ms. Brose, who first met him when he worked at a Roy Rogers outlet in the first floor of the old St. Francis Hospital in Lawrenceville.

"He lives in those neighborhoods," she said. "The bottom line is he wants the streets to be clean and for the streets to be safe.

"But he has to understand one thing: He can't do it all."

Upon hearing the news, Archbishop Donald W. Wuerl of Washington, D.C., the recent bishop of Pittsburgh, offered his prayers for the Mayor and his family.

"I was very distressed to learn of the physical condition of Mayor -- and my good friend -- Bob O'Connor, and I want to assure him, his wife Judy, and their sons Fr. Terry and Cory, of my prayers and support. I feel very close to them and particularly to Bob, even though I am not able to be with them in Pittsburgh."

Mayor O'Connor attended the June 22 installation of Archbishop Wuerl in Washington.

Auxiliary Bishop Paul Bradley, who is serving as administrator of the Pittsburgh diocese until a new bishop is appointed, called on people of all faiths to pray.

Added former mayor Sophie Masloff, who ascended to mayor when Richard Caliguiri died in 1988, "The Lord works in strange ways. All we can do is hope for the best.''

Post-Gazette staff writers Jerome L. Sherman and James O'Toole contributed to this story. More details in tomorrow's Pittsburgh Post-Gazette.