Divided by politics, but united in grief<br/><span class='hl2'>McCain, Obama pay tribute at Ground Zero.</span>

NEW YORK — For one rare day, presidential candidates John McCain and Barack Obama made Ground Zero their common ground, free of politics and infused with memory.

Putting their partisan contest on a respectful hold, they walked together Thursday into the great pit where the World Trade Center towers once stood and, as one, honored the dead from the terrorist attacks of Sept. 11, 2001.

They laid flowers at the pit's commemorative reflecting pool. There were no speeches.

However, left unsaid by both was their sharp disagreement over the Iraq war, which McCain supported and Obama opposed as a distraction from the Afghanistan war.

Biden, Palin's day

Obama's running mate, Joe Biden, visited an American Legion post in suburban Cleveland for an invitation-only gathering of area police, firefighters and other first responders.

"Part of today is reminding Americans that every single day there are acts that are both ordinary and profound,” Biden said. "You suit up, head out on that vehicle not knowing what you're going to find. If, God forbid, anything remotely close to that happens, it's going to be you guys trying to save all of us.”

Republican vice presidential candidate Sarah Palin was in her home state of Alaska to attend an Army ceremony to send her eldest son, Track, off to Iraq.

Obama and McCain intersected later in the evening, at a Columbia University forum on public service. The candidates' sessions were separate, joined only by a handshake.