Washington --  Arlen Specter, the irascible senator from
Pennsylvania who was at the center of many of the Senate's most
divisive legal battles - from the Supreme Court nominations of
Robert Bork and Clarence Thomas to the impeachment of President
Bill Clinton - only to lose his seat in 2010 after quitting the
Republican Party to become a Democrat, died Sunday at his home
in Philadelphia.  The cause was complications from non-Hodgkin's
lymphoma, said his son Shanin. He was 82.  Hard-bitten and
tenacious yet ever the centrist, Sen. Specter was a part of
American public life for more than four decades. As an ambitious
young lawyer for the Warren Commission, he took credit for
originating the theory that a single bullet, fired by a lone
gunman, had killed President John Kennedy.  Sharp legal mind
Yet he may be remembered best for his quixotic party switch in
2009 and the subsequent campaign that cost him the Senate seat
he had held for almost 30 years. After 44 years as a Republican,
Sen. Specter, who began hi