wikipedia

Voter suppression are tactics used to discourage or prevent specific groups of people from voting or registering to vote. It is distinguished from political campaigning in that campaigning attempts to change likely voting behavior by changing the opinions of potential voters through persuasion and organization, activating otherwise inactive voters, or registering new supporters. Voter suppression, instead, attempts to gain an advantage by reducing the turnout of certain voters. Suppression is an anti-democratic tactic associated with authoritarianism.