After arguing during the campaign that Democrats would undermine national security, President Bush changed course Saturday and said America's enemies should not read this week's ground-shaking election results as a sign of U.S. weakness. Four days after voters threw Republicans from power in the House and Senate, Bush used his weekly radio address to issue a call for unity. "The message of this week's elections is clear: The American people want their leaders in Washington to set aside partisan differences, conduct ourselves in an ethical manner and work together to address the challenges facing our nation," the president said. "This...