The president may find it difficult to combine his role as the head of
what Bagehot called the "deferential" or symbolic aspect of the polity (a
role that Bagehot thought the British monarch played perfectly and
which, in republican parliamentary constitutions, has been successfully
filled by presidents such as Sandro Pertini of Italy and Theodor Heuss
of West Germany) with his role as an effective chief executive and
partisan leader fighting to promote his party and its program.