(Ali Jarekji ) US Democratic presidential candidate Senator Barack Obama gestures during a news conference at the Amman Citadel, an ancient Roman landmark, in Amman, Jordan, July 22, 2008 Barack Obama’s campaign for the presidency is scrambling to stem a stream of false allegations modelled on the “Swift Boat” smears that helped to defeat the last Democratic nominee, John Kerry, four years ago. A new book written by Jerome Corsi, entitled The Obama Nation, leapt to No 1 in the bestseller lists this week with claims that the Illinois senator is a closet Muslim, a black militant and takes...