US President Barack Obama speaks during a campaign rally in Columbus, Ohio, on November 5, 2012. After a grueling 18-month battle, the final US campaign day arrived Monday for Obama and Republican rival Mitt Romney, two men on a collision course for the world's top job. The candidates have attended hundreds of rallies, fundraisers and town halls, spent literally billions on attack ads, ground games, and get out the vote efforts, and squared off in three intense debates. Credit: AFP/Getty Images