W A S H I N G T O N, June 24 — Sen. John McCain vowed Monday to block confirmation of all Bush administration nominations until a replacement is installed for a lame duck Federal Election Commission member who helped approve controversial campaign fund-raising rules. In a letter to Senate leaders, the Arizona Republican pledged to object to action on "any nominee" unless Ellen Weintraub is confirmed by early August or President Bush agrees to bypass the Senate and make the appointment on his own.Weintraub is in line to replace Karl Sandstrom as one of three Democratic members on...