PENGKALAN PASIR, Malaysia (Reuters) - Malaysia's ruling coalition sought to push the nation's fundamentalist Islamic party further into the political wilderness on Sunday with the start of its campaign for a crucial state by-election. Prime Minister Abdullah Ahmad Badawi's Barisan Nasional coalition is contesting the Dec. 6 poll in northeastern Kelantan state, the last stronghold of Parti Islam se-Malaysia (PAS), which rules the state legislature with a two-seat majority. The poll in the rural state seat of Pengkalan Pasir is the first since Abdullah won a thumping general election victory in early 2004 on a pledge to clean up corruption...