President Obama casts early vote in Chicago

President Barack Obama has cast his vote in his hometown of Chicago as his campaign seeks to boost early ballots in a neck-and-neck election race.

Mr Obama, who is on a two-day campaign marathon across eight states, is the first president to vote early.

His Republican challenger, Mitt Romney, is in Ohio, a swing state which could hold the key to the White House.

After casting his vote, Mr Obama thanked the staff at the polling station and joked "I can't tell you who I voted for".