Restoring the old era of smoke-filled rooms is neither possible nor desirable. Primaries bring important information to the nominating process. They test candidates’ ability to excite voters and campaign effectively; they provide points of entry for up-and-comers and neglected constituencies; they force candidates to refine their messages and prove their stamina. But as 2016 made clear, primaries are only half of a functional nominating system. The other half is input from political insiders and professionals who can vet candidates, steer them to appropriate races, and, as a last resort, block them if they are unacceptable to the party or unfit to govern.

The Democrats’ 2020 race may well avoid a descent into chaos. The desire to unseat Trump may encourage primary voters to coalesce around a candidate with a traditional résumé and broad appeal. The field appears to be narrowing to such candidates. While party elders can hope for a rational outcome, however, nothing in the process guarantees one. In 2016, mandarins in the Republican Party assumed, until it was too late, that its primary electorate would eventually reject Donald Trump. Both parties’ presidential-nominating contests have reached a point where they cannot promise to choose nominees who are competent to govern or who represent a majority of the party’s voters.

Political professionals—insiders such as county and state party chairs, elected officials such as governors and legislative leaders—are uniquely positioned to evaluate whether contenders have the skills, connections, and sense of responsibility to govern capably. Only they can do the brokering and bridge-building to form majorities and shape coalitions, and to ensure that the nominee is acceptable to a broad cross section of party factions. Only they can reduce the element of sheer randomness that plagues today’s primaries, where a stroke of bad luck in a single state can sink a candidacy. The voters need their help.