Press Association: Climate change campaigner and former vice president candidate Al Gore has accused the US of blocking progress at the Bali talks. But he remained optimistic that a breakthrough was possible in the final days of the conference aimed at finding a successor to the Kyoto agreement. "Some of the reports are worrisome, but I know from experience … that when breakthroughs do occur, they usually happen in the last 48 hours," the Nobel Prize winner said. "I hope …