(Adds details, Obama meeting with Clinton) By Jason Szep and Caren Bohan NEW YORK, Sept 11 (Reuters) - Presidential rivals John McCain and Barack Obama suspended their fierce political skirmishing on Thursday in honor of the seventh anniversary of the Sept. 11 attacks, and made a rare appearance together. Taking a breather from their campaign-trail feud, Republican McCain and Democrat Obama refrained from airing political ads for one day and came together at the site of the World Trade Center attacks in New York. They shook hands and walked shoulder to shoulder down a 482-foot (147-metre) ramp into the Ground Zero area, where they greeted police officers and rescue workers at a memorial site, as Americans honored the nearly 3,000 victims of the attacks in ceremonies in New York, Pennsylvania and at the Pentagon. When they met, McCain patted Obama's back and said, "Good to see you." New York Mayor Michael Bloomberg and McCain's wife, Cindy, walked behind them down the ramp. The two candidates for the Nov. 4 election each laid roses in a flower-covered pool and bowed their heads. Relatives of victims of the attack greeted them at the site that included a temporary memorial with two wooden squares representing the twin towers rising from a pool of floating roses. Later, they were to appear separately at a forum on service in New York. McCain attended a morning memorial in Shanksville, Pennsylvania, where one of the hijacked airliners crashed in a field during a struggle as passengers on United Airlines Flight 93 battled the hijackers to take control of a plane believed headed for the U.S. Capitol. "No American living then should ever forget the heroism that occurred in the skies above this field on September 11, 2001," McCain, an Arizona senator, said before laying a wreath at the site and joining an annual reading of passenger names as bells tolled. 'NEVER FORGET' Obama, an Illinois senator, said those who died would not be forgotten. "We will always remember the heroic efforts of our firefighters, police and emergency responders, and those who sacrificed their own lives on Flight 93 to protect their fellow Americans," he said in a written statement. Obama did not halt campaign activity entirely. Earlier, he had lunch with former President Bill Clinton who agreed to campaign for him. "I predict that Senator Obama will win and will pretty handily," Clinton told reporters. "There you go," Obama added. "You can take it from the president of the United States. He knows a little something about politics." A CNN poll released on Thursday showed the threat of terrorism was the fourth most important issue for U.S. voters, behind the economy -- picked by more than half -- and the Iraq war and health care. McCain, a former Vietnam prisoner of war, is heavily favored over Obama by voters to handle security and foreign policy issues, opinion polls show. Until recently, McCain stressed his national security expertise and criticized Obama as too inexperienced for the White House. He has shifted his argument since picking Alaska Gov. Sarah Palin as his running mate, portraying their ticket as the true agents of change in the White House election. (Writing by John Whitesides and Jason Szep; Editing by Peter Cooney)
