Potential demagogues exist in all democracies, and occasionally, one or more of them strike a public chord. But in some democracies, political leaders heed the warning signs and take steps to ensure that authoritarians remain on the fringes, far from the centers of power. When faced with the rise of extremists or demagogues, they make a concerted effort to isolate and defeat them. Although mass responses to extremist appeals matter, what matters more is whether political elites, and especially parties, serve as filters. Put simply, political parties are democracy's gatekeepers.