For anyone concerned about democratic norms and the rule of law, the 2016 election offered a clear lesson: Parties need to exercise more control over candidate selection. In this era of high partisanship, the official party nomination puts any candidate within striking distance of the presidency. This great power thus carries a profound responsibility: to deny the party endorsement to would-be demagogues. So why are Democrats reducing the role of party elites in the primary process this time around?