The Pew Research Center for the People & the Press today released the latest national poll that shows a nip-and-tuck presidential race. Democrat Barack Obama leads Republican John McCain 46 percent to 43 percent among registered voters, barely outside the poll's margin of error. Obama's edge is down from 48 percent to 40 percent in the same poll in June and 47 percent to 42 percent last month. "Two factors appear to be at play in shifting voter sentiment," the pollsters say. "First, McCain is garnering more support from his base - including Republicans and white evangelical Protestants - than...