Both President Barack Obama and Republican challenger Mitt Romney plan to take down their negative ads in honor of the 11th anniversary of the 9/11 terrorist attacks. Neither planned to appear at overtly political events, although Election Day is never far from their agendas.

Obama has scheduled a moment of silence at the White House and a trip to the Pentagon, the target of one of four planes al Qaeda hijacked 11 years ago. Romney, meanwhile, is set to address the National Guard, whose members deployed as part of the U.S. response to the attacks.

"On this most somber day, those who would attack us should know that we are united, one nation under God, in our determination to stop them and to stand tall for peace and freedom at home and across the world," Romney said in a statement released before his speech. "Today we again extend our most profound gratitude to our brave troops who have gone into battle, some never to return, so that we may live in peace."

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