NEW YORK — Sens. Barack Obama and John McCain pledged to inspire a new commitment to public service yesterday, as they set aside the rancor of an intense presidential campaign during a two-hour forum on the seventh anniversary of the Sept. 11 attacks.

"The best way to commemorate, and the best way to show our appreciation for and our love and sympathy for the families of those who have sacrificed, is to serve our country," McCain said.

The question, Obama said later, is how to recreate the spirit of service "not just during times of tragedy, not just during 9/11, but how do we honor those who died, those who sacrificed ... how do we honor them every day?"

In back-to-back conversations largely devoid of partisan recrimination, McCain and Obama each urged Americans to honor the victims of the country's worst terrorist attack by dedicating their time to service through teaching, the military, the Peace Corps and faith-based volunteering.

But the reality of Campaign 2008 was never far from the surface as both men were challenged by the questioners to explain the often angry tone of their competition for the White House.

McCain acknowledged the "rough" nature of the campaign and praised Obama's service as a community organizer — something his vice presidential nominee, Alaska Gov. Sarah Palin, had mocked during her speech to the Republican National Convention.

McCain defended Palin, saying she had been responding to a barrage of criticism of her own experience as a small town mayor. But he appeared to chide his supporters who derided Obama's efforts as a young man.

"Of course I respect community organizers. Of course I respect people who serve their community," he said.

Obama declined to disparage Palin's service as mayor of Wasilla, praising small-town mayors and noting the presence of many at the Democratic National Convention in Denver last month. "We yak in the Senate. They actually have to fill potholes, trim trees and make sure the garbage is collected," Obama said.

Obama called McCain's service in the military "legendary," adding that "one of the wonderful things about this campaign is his ability to share that story."

Some of the more lighthearted moments of the evening came when both men were asked if they would create a Cabinet level position on public service — and then appoint the other to it.

McCain chuckled and jokingly said "Yes," before adding that he believes there are too many Cabinet secretaries already.

Obama laughed and said, "If this is the deal he wants to make right now, I'm committed to appointing him." Asked whether he would serve in McCain's Cabinet, Obama said "We've got a little work to do before we get to that."

While the tone of the event was civil, McCain and Obama did outline differing roles for the federal government on volunteerism.

McCain stressed that the government should not compel service and argued the private sector should take a larger role in disaster relief.

"When you compel someone to do something, you basically are in contradiction to the basic principle of people wanting to serve," he said.

Obama, who has proposed a $3.5 billion service program, emphasized his belief that government and the private sector could work together to augment the others' efforts. The solution, he said, is to offer people more ways to volunteer.

"My sense is the country yearns for that," Obama said. "It's hungry for it. What has been missing is a president in the White House that taps into that yearning in a serious way. ... The choices we offer young people today are too constraining."

Each made a bit of news in the forums.

McCain pledged to sign a bipartisan bill on national service that is being introduced today, prompting applause from the audience at Columbia University.

Obama said it was wrong for Columbia — his alma mater and the host of the event — and others to turn away the ROTC because of differences some students have on military policy.

"I think we've made a mistake on that," he said. "We should have an honest debate while still having opportunities to serve."