Sept. 12 (Bloomberg) -- John McCain and Barack Obama found common ground on the virtues of volunteering at a forum on national service last night that ended a day largely free of the partisan broadsides that will define the presidential campaign over the next 53 days.

Republican nominee McCain, appearing first, extended an olive branch to his Democratic rival, saying he respects Obama's record as a community organizer. He suggested that if he wins the election he would invite the Illinois senator to lead a national service effort. Obama responded in-kind.

``Of course I respect people who serve their community and Senator Obama's record there is outstanding,'' McCain said at the forum at Columbia University in New York.

Returning McCain's goodwill, Obama said he respected Republican vice-presidential nominee Sarah Palin's experience as a small-town mayor. Mayors ``have some of the toughest jobs in the country,'' he said.

``We yak in the Senate,'' Obama said. ``They actually have to fill potholes and trim trees and make sure the garbage is taken away.''

McCain and Obama appeared separately and were on stage together briefly to shake hands and embrace. It was a shorter version of their joint appearance earlier in the day, when they took part in a ceremony at Ground Zero, the site where the World Trade Center towers collapsed, on the seventh anniversary of the Sept. 11 attacks. They threw flowers on a reflecting pool located in what is now a construction zone for a memorial.

Temporary Truce

While the two candidates put aside political rivalry to mark the anniversary, the truce won't last.

``Today was non-partisan,'' Democratic Representative Jerrold Nadler of New York said. ``The election is not going to be non-partisan.''

Both candidates ``avoided talking about the real issues that will define the campaign,'' he said, adding that the niceties likely would end ``within hours.''

Obama's past as a community organizer became a contentious issue in the campaign after McCain's running mate and other speakers at the Republican National Convention last week derided his experience. Responding to criticism that her own resume was built on a job as the mayor of Wasilla, Alaska, Palin said: ``I guess a small-town mayor is sort of like a community organizer, except that you have actual responsibilities.''

Surprised by Barb

Obama, 47, said he was ``surprised'' by Palin's barb, calling community service ``the best education I ever had'' and ``something I want to encourage for every young person.''

McCain said that while the work Obama did in Chicago after graduating from college should be lauded, politics ``is a tough business.''

``I think the tone of this whole campaign would have been very different if Senator Obama had accepted my request'' to hold a series of joint appearances at town hall-style events, McCain, 72, said. Palin, he said, was responding to criticism from Democrats about her own background.

McCain answered with a short ``yes,'' when asked if he would invite Obama to serve in his administration at the Cabinet level to direct a national service effort. The Arizona senator didn't elaborate, though his response drew laughter from the audience.

Asked the same question, Obama gave a similar answer. ``I mean, if this is the deal he wants to make right now,'' said Obama, as the audience interrupted him with laughter, ``I am committed to appointing him to my cabinet of national service.''

ROTC

McCain also reprised his criticism of Ivy League institutions for barring Reserve Officer's Training Corps from campus. Participants in ROTC join the military after graduation.

``We're here in a wonderful institution,'' McCain said, noting that his daughter graduated from Columbia. ``But do you know that this school will not allow ROTC on this campus?''

``I don't think that's right,'' he said. ``Shouldn't the students here be exposed to the attractiveness of serving in the military, particularly as an officer?''

When it was his turn for the same question, Obama, who got his undergraduate degree from Columbia, agreed with McCain.

``I recognize that there are students here who have differences in terms of military policy,'' Obama said. ``But the notion that young people here at Columbia or anywhere, in any university, aren't offered the choice, the option of participating in military service, I think is a mistake.''

McCain and Obama attended the forum after several days during which their campaigns accused each other of making unfair attacks. The presidential race has also tightened; McCain erased a lead Obama had after the Democratic Party convention ended in late August and has taken a lead in some national polls. They are tied in others.

Obama plans to return to New York on Sept. 13 to appear on NBC's comedy sketch show ``Saturday Night Live.'' McCain today will make the rounds on daytime television programs, taping appearances on ABC's `The View'' and the syndicated Rachael Ray show.

To contact the reporters on this story: Hans Nichols in New York at hnichols2@bloomberg.net; Kristin Jensen in New York at kjensen@bloomberg.net

Last Updated: September 12, 2008 00:22 EDT