[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/POLITICS/10/31/october.surprise/art.kerryreax.ap.jpg caption="Reporters pressed Kerry about the Osama bin Laden tape. "](CNN) - It's Halloween on Friday, but campaign aides to Barack Obama and John McCain may be spooked for another reason: Events that dominated the news in the dwindling days before the previous two presidential elections may have been game-changers.
Aides to Sen. John Kerry were increasingly confident of victory four days before the 2004 election, believing the Massachusetts senator performed strongly in three debates with President Bush and was buoyed by polls showing a last-minute surge for the Democratic ticket.
But that was before Osama bin Laden weighed in.
On Friday, October 29, the 9/11 mastermind released a videotape to Arab television network al-Jazeera, in which he condemned President Bush's response to the 9/11 attacks and told the American people, "Your security is in your own hands."