Senators Obama and McCain, while praising the role of community service in American society, are indicating that they differ broadly in their thinking on the role government should play in encouraging service work and tapping into the spirit of service that flourished in the aftermath of the terrorist attacks of September 11, 2001.

Speaking at a forum at Columbia University on service and citizenship held last night on the seventh anniversary of the attacks, Mr. Obama said he favors a more expansive role for government when it comes to encouraging community service work, while his opponent in the presidential campaign, Mr. McCain, said he is opposed to having the government run a host of new programs.

The candidates’ remarks came at the end of a joint visit to New York, during which the senators together paid their respects to those killed on September 11 at ground zero.

Messrs. Obama and McCain had promised to suspend their political attacks for a day to honor the memory of the deceased, but the friction from the increasingly bitter campaign battle did surface during the forum, with Mr. McCain blaming his opponent for the divisive turn in the race.

“I think the tone of this whole campaign would have been very different if Senator Obama accepted my request for us to appear in town hall meetings all over America,” Mr. McCain said at the forum.

The candidates spoke on the same stage, but shared it for only a brief moment during the break between their individual, sit-down conversations with the evening’s moderators, an editor of Time magazine, Richard Stengel, and a senior correspondent with PBS, Judy Woodruff.

Mr. McCain, responding to a question about his running mate’s derision of community organizers during the Republican convention, said he respects community organizers and said Mr. Obama’s record in that area is outstanding. Mr. Obama, who was a community organizer in Chicago after graduating from Columbia, later praised the work of small town governors, saying that they have some of the toughest jobs in the country. Governor Palin, the Republican vice presidential candidate and former mayor of a small Alaska town, has faced criticism from Democrats who say she is inexperienced.

When the conversation with each senator turned to military service, the candidates indicated that they share common ground on the issue of Columbia’s ban on ROTC programs on campus, with both denouncing it.

Mr. Obama said that while he recognizes that there is debate among students over the country’s military policy, it is a mistake to not give people the opportunity to participate in military service.

The candidates both have strong connections to the university. It is Mr. Obama’s alma mater and the school that Mr. McCain’s daughter attended. Governor Paterson, another graduate of Columbia, spoke at the outset of the forum, saying that America is fortunate to have two presidential candidates with outstanding records of service throughout their careers, noting Mr. Obama’s rejection of lucrative professional opportunities to work in service organizations in Chicago and Mr. McCain’s military service, when he “almost had to offer the ultimate service” as a prisoner during the Vietnam War.

The coordinated appearances by the candidates were designed to project an image of bipartisan cooperation and respect on a day that many Americans say they want to be free of politics.

Mayor Bloomberg, a former Republican who had toyed with the idea of running for president, had an opportunity to project his nonpartisan mantra during the visit, acting as an escort to the candidates when they stopped by ground zero in the afternoon. He has not endorsed either candidate, but has been pressing both to explain to the public exactly how they plan to solve the nation’s problems.

At around 4 p.m., Messrs. McCain and Obama descended into the World Trade Center site, walking side by side down a wide ramp that was flanked with international flags. Mr. McCain’s wife, Cindy, and the mayor followed a few steps behind, strolling arm-in-arm.

The political rivals stopped to speak to relatives of those killed in the attacks, before placing flowers in a reflecting pool and standing, side-by-side, with their heads bowed over the pool.

Politics never seemed too far from either senator’s mind yesterday. Mr. Obama met with President Clinton for nearly two hours at the former president’s Harlem office on 125th Street, telling reporters before the meeting began: “We’re putting him to work.”

Mr. Clinton, when asked for his thoughts on the race so far, said he predicted that Mr. Obama would “win and win pretty handily.”

The McCain campaign yesterday announced that it is beginning to shore up its support among local Latino voters, saying it is holding a rally in Manhattan today to kick off its New York and New Jersey Latino coalition.

In Lower Manhattan’s Zuccotti Park, during a morning service for the relatives of those killed in the attacks of September 11, people gathered to remember the lives of the deceased were divided on whether the candidates’ visit to the ground zero was a good idea.

Frances Bulaga of Wanaque, N.J., said she was at the ceremony for her son, John Bulaga Jr., who had worked on the 103rd floor of Tower One for Cantor Fitzgerald. She said she didn’t want to talk about politics, but that she thought it was wrong for the candidates to visit on the anniversary of the attacks.

“Tomorrow’s another day. They could do it tomorrow,” she said. “They don’t have to take away from what we are doing today.”

Kerene Reeves, 27, who lost her mother, a former employee of an insurance brokerage company in Tower Two, to the attacks, said she thought it was important, however, to have them there.

“I’m glad they are aware of the hurt and the fact that this is a delicate and tragic event,” she said.

At a remembrance service for members of the Port Authority of New York and New Jersey who died on September 11, Mr. Bloomberg sought to connect the presidential campaign to the anniversary, saying that the terrorists who attacked New York seven years ago don’t understand our political system.

“They look at our intense campaigns, they hear the strong arguments we express with each other, and they see disunity and weakness. That’s a profound misunderstanding of who we are. It is our very ability to disagree that keeps us strong and in the end unites us as Americans,” he said.

He added that between today and Election Day, Americans will express their disagreements, but that after the votes are counted will come together “just like we did on 9/11.”

“Just like we always will when our nation is tested,” he said.