Ever since the birth of the modern presidential nominating process, in 1972, in which most delegates were chosen via primaries and caucuses and not by party bosses, there has been an important period called—in the words of the journalist Arthur Hadley—the “invisible primary.” This was the period between the last ballot in one general election and the first ballot in the first primary of the next. During this time, candidates travel the country trying to win the support of party leaders, single-issue organizations, activists, potential staff members, interest groups, community leaders, donors, and elected officials—that is, the party.

This invisible primary was clearly visible only to those most involved in Democratic Party politics. Over the years, and especially as Democrats repeatedly lost national elections in the 1980s, some complained that this put an emphasis on candidates who could court the more liberal parts of the party. Study after study has shown that those most active in Democratic Party politics hold views to the left of the party’s rank and file (and that similarly, the GOP’s primary voters are to the right of the Republican Party’s rank and file).

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Nevertheless, the success of some candidates in generating support among those most active in party politics sent a powerful signal to voters about their viability in the general election. As the political scientists Marty Cohen, Dan Karol, Hans Noe, and John Zaller have argued, the party was unusually effective from 1980 onward in preventing non-establishment candidates from winning—including Ted Kennedy, Jesse Jackson, and Howard Dean. These candidates weren’t forbidden from running; in fact, they all ran spirited races. But the party exercised real influence over the selection of a nominee, even though it had no official role until the Iowa caucus.

One might think that Democratic Party leaders, watching Republicans standing by as Donald Trump—a onetime Democrat whose positions and values were at odds with those long articulated by the GOP—won the nomination with less than 45 percent of the vote, would have seen the importance of this role. Yet instead of bolstering its safeguards against a non-establishment candidate seizing the nomination, the DNC instead chose to change the rules in a way that put greater power into the hands of online activists.

Like most rules reforms, these changes were intended to solve one problem, and ended up creating another. The DNC was attempting to bring some order to a season of debates and forums that seemed overrun with both events and candidates. It instituted two qualifying criteria: polling performance and online fundraising. By choosing these two measures (and not, say, endorsements from labor unions and elected officials), party officials put a premium on candidates’ name recognition, and their ability to appeal to online activists.