NABLUS, West Bank - Palestinian gunmen linked to the ruling Fatah movement killed one of their party leaders Tuesday, increasing tensions on the eve of parliamentary balloting and raising doubts about a new pledge by armed groups in the West Bank and Gaza to hold their fire during the vote. Opinion polls have shown Fatah and Hamas in a close race ahead of Wednesday's election and both sides have said they might form a coalition government. Candidates were banned from campaigning Tuesday for a cooling-off period before the election. Mushir al-Masri, a Hamas candidate in northern Gaza, said the Islamic...