One who uses popular biases and other aspects of cultural programming to elicit a "knee-jerk reaction" from a crowd or audience, avoiding the dispassionate examination of the facts related to some issue, in order to ascend to leadership.
Also demagogue, from the Greek demos 'people' + aggos 'leading'
In ancient Greece, one of the common purposes of logical argument was to deflate the rhetoric of a demagogue.
Despite the harmful divisions created, G.W. Bush chose to act as a demagogue rather than lose re-election.