Presumptive U.S. presidential nominees Senator John McCain (R-AZ) and Senator Barack Obama (D-IL) are shown in this combination of file photographs from campaign stops from July 18, 2008 in Warren Michigan (McCain) and August 4, 2008 (Obama) in Lansing, Michigan. Obama and McCain have agreed to speak at a New York City forum on public service to be held on September 11, the organizers said on Thursday.
(Rebecca Cook/Files/Reuters)