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.
A leader who obtains power by means of impassioned appeals to the emotions and prejudices of the populace. In other words, a person who lies and manipulates a crowd by giving them false hopes by just telling them what they want to hear, no matter how outrageous and wrong it is. Usually done to gain votes. see liberal
Look at that demagog over there, brainwashing those ignorant people!