Political scientist Julia Azari has an essay on Vox explaining the rise of Trump in terms of “weak parties and strong partisanship:”
The defining characteristic of our moment is that parties are weak while partisanship is strong…. it is a particularly dangerous combination [because] parties can’t control whom they nominate. But their adherents — elites and ordinary voters alike — are prepared to support them.
Why is this a very bad combination? It encourages polarization between parties, and a heightened sense that people who belong to other parties, and the candidates they support, are evil. It creates an environment in which partisan voters can be mobilized to vote against the opposition even if they have strong reservations about their own candidate. It means that the apparatus of a political party can more easily fall into the hands of someone who doesn’t believe in the party’s major principles, but succeeds in appealing to its rank and file.
And it also makes moderation much less likely in governing. Compromise with the other party seen as weakness, but each side is less likely to have things that the other wants or needs. As ideological purity becomes more important, it becomes more dangerous for politicians to engage in bipartisan deals, or to be seen as wavering or uncertain in their ideological commitment. And partisanship undermines institutions. As Azari puts it, “It’s hard for institutions — elected ones like Congress, the presidency, or state governments,” or for “courts and, as we’ve seen most recently, law enforcement agencies” to be seen as trustworthy when citizens are inclined to “view much of what these institutions do through a partisan lens.”
And of course the bad news here is that the structural forces that gave rise to Trump are either not going to go away if he loses, or will overwhelm to GOP and Washington if he wins. One is hard pressed to imagine a cabinet consisting of his most ardent supporters and apologists serving as a balance against his authoritarian tendencies; and Capitol Hill hasn’t exactly been Profiles in Courage so far either.