Former New York Sen. James Buckley, an early agitator for then-President Richard Nixon's resignation and winner of a landmark lawsuit challenging campaign spending limits, died Friday at age 100. Buckley died at a hospital in Washington, D.C., according to his son David Buckley of Arlington, Virginia. Buckley was the fourth of 10 children of a millionaire oilman and older brother of conservative commentator William F. Buckley Jr., who died in February 2008.