Sen. Elizabeth Warren. (Sarah Rice/The Washington Post)
Contributing opinion writer

With the Democratic presidential primary about to start and with so many candidates about to declare, what should we look for as the race unfolds? It may be useful to think of the Democratic contest not as one long, sequential event, but as a series of mini-contests with multiple candidates fighting to win key “pre-primaries” before the actual voting begins. This has long been true: In years past, there was the “money” primary to lock up key financial backers; the “operative” primary to win over the hottest consultants; the labor primary to secure that key group of Democratic foot soldiers and monetary support, and so on.

These mini-primaries still matter, but new ones will emerge. The Democratic Party has changed dramatically since 2004, the last time there was a crowded primary field. Today’s Democrats are less white, more college-educated, more suburban and, perhaps most relevant, more liberal.

The mechanics of campaigning have also changed; candidates such as Howard Dean, Barack Obama, Bernie Sanders and Beto O’Rourke have shown the power that online organizing and fundraising have to level the playing field. Finally, as a direct result of Donald Trump, the energy and passion within the Democratic Party are at a peak not reached since 1968, when Democrats were riled and riven by the Vietnam War.

Today’s possible and likely Democratic candidates fall into certain categories. There are the progressives — Sanders, Warren, Sen. Kamala D. Harris and Rep. Tulsi Gabbard of Hawaii; the “executives” — Michael Bloomberg, Colorado Gov. John Hickenlooper and former Virginia governor Terry McAuliffe, whose candidacies will be based in part on a claim of having governed successfully; the “political transcendentalists” — Rep. Beto O’Rourke, Sen. Cory Booker, Howard Schultz — who will run as outsiders with a post-partisan approach; the “female majority” candidates — Sens. Kirsten Gillibrand and Amy Klobuchar, who will make equality for women the central economic platform of their campaigns; and the “traditionalists” — former vice president Joe Biden and Sen. Sherrod Brown, who will speak to that shrinking, but still important, constituency in the party, the working class.

These categories are, of course, somewhat arbitrary. Most of the candidates and their handlers would, with some justification, bitterly resist this typecasting and narrowing of their appeal, but they are useful, nonetheless. With so many candidates, voters themselves are going to default to archetypes to try to make sense of the field, and there is simply isn’t enough political oxygen for multiple progressives, executives, traditionalists and outsiders to last beyond the New Hampshire primary. The winnowing will be rough. For the next year, the goal of each Democratic candidate for president will be to become the leader of a power source within the party and win the right to compete in South Carolina and the slew of primaries soon after.