Illustration by Alex Merto Illustration by Alex Merto Illustration by Alex Merto Illustration by Alex Merto

By Jason Zengerle a contributing writer for The New York Times Magazine and the political correspondent for GQ.

Every senator looks in the mirror and sees a future president. But these days, for Democrats at least, it’s not just members of Capitol Hill’s upper chamber who are picturing themselves sitting in the Oval Office. Congressmen, governors, mayors, even people who hold no elected office — men and women at seemingly every rung of the political ladder, including no rung at all — are suddenly eyeing the White House.

For this, Democrats can thank (or blame) Donald Trump. His election in 2016 showed that the barriers to entry to the White House weren’t nearly as formidable as political professionals once assumed. More important, Mr. Trump at the moment seems eminently beatable, with an approval rating hovering just south of 40 percent. No other president in the era of approval polling (going back to the 1930s) has been this unpopular at this point in his presidency.

A result is that the Democratic presidential field in 2020 may be even bigger than the unwieldy Republican 17-member parade in 2016. Indeed, a recent informal survey of Democratic strategists produced a list of more than 30 fellow party members who are — or who, in the minds of these insiders, should be — thinking about running for president in 2020.

Although Democrats are united in their opposition to President Trump, the fundamental party cleavage runs between populists and centrists. The Democratic presidential nominee in 2020 will be the person who either finds a way to appeal to both wings or, just as likely, divines which wings represent the greater number of primary voters. Following is a guide to some of the potential candidates — and the political bets they’ll be making.

THE B.W.H.W. CANDIDATES

A literature of alternative histories has sprung up about Democratic candidates other than Hillary Clinton who would have won in 2016. The two most popular titles in this genre? “Bernie Would Have Won” and “Biden Would Have Won.” Are they viable for 2020?

A recent poll put Bernie Sanders’s approval rating at 75 percent, which makes him the most popular politician in America. He’s the standard-bearer for the populist left whose “Medicare for All” bill, while still a liberal pipe dream, now seems as much of a litmus test for ambitious national Democrats as abortion rights. He will also be 79 years old on Election Day 2020.

Joe Biden, a son of Scranton, Pa., appeals to the same working-class white voters who flocked to Mr. Trump in 2016. Some progressives no doubt look upon him fondly from his days as Barack Obama’s vice president. But Mr. Biden’s three-decades-long centrist Senate record, from his handling of Clarence Thomas’s confirmation hearing in 1991 to his vote for the 2005 bankruptcy bill, might make him a tough sell to today’s Democratic primary voters, not to mention the fact that he still has those centrist tendencies (he recently came out against a universal basic income). And he’ll turn 78 in November 2020.

Would Mr. Sanders or Mr. Biden have won in 2016? We’ll never know — but it’s unlikely either will in 2020.

THE PARTY POPULISTS

As a democratic socialist, Senator Sanders has no real allegiance to the Democratic Party; it often seems his populist movement would just as soon burn the party down. But there are other populists who are less antagonistic to the Democratic Party — not to mention who actually belong to it.

If she runs, Elizabeth Warren, a Massachusetts senator, would instantaneously be the Democrats’ putative front-runner. Her anti-corporate agenda has made her a fund-raising powerhouse, and she seems to have found an ideological sweet spot between the centrist Clinton and populist Sanders factions. Additionally, thanks to the “Nevertheless she persisted” meme, she’s become a feminist heroine.

But Ms. Warren, who’ll be 71 in 2020, is an ambivalent politician — a longtime law professor, she didn’t run for office until 2012 — and it’s not clear that she has the proverbial fire in the belly for a presidential bid.

Sherrod Brown, an Ohio senator, hails from a crucial swing state and has strong labor backing. He’s never seemed interested in a presidential run — until now. A finalist in the 2016 Democratic veepstakes, he would be formidable in Rust Belt states. His politics match the mood, and while he might not have the raw talent of Senator Warren, he’d be a strong Plan B.

And if the populist wing is looking for a Plan C, Senator Jeff Merkley of Oregon humbly suggests himself. He was the only senator to endorse Mr. Sanders in 2016, has been spending a fair amount of time in Iowa of late, and has become the go-to guy on Capitol Hill for liberal groups like MoveOn.

THE (RELUCTANT) ESTABLISHMENTARIANS

Being the establishment candidate in the current political climate is the kiss of death. Which is why even candidates who fit that mold will do everything they can to avoid the label — including co-sponsoring Mr. Sanders’s Medicare for All.

Mr. Booker, a New Jersey senator, has seemingly been running for president since he was a Rhodes scholar at Oxford in the ’90s. But some of the well-heeled backers he picked up along the way — including Big Pharma and Jared Kushner and Ivanka Trump — are now political poison in a Democratic primary. He may end up spending as much time distancing himself from his old supporters as cultivating new ones.

Ms. Gillibrand, a New York senator, is similarly well liked on Wall Street. She’s recast herself as a tough-talking liberal in recent years — introducing legislation that would institute paid family leave — but her obligations to the financial services sector will hamper her.

Ms. Klobuchar, a Minnesota senator, claimed national attention as a sort of thinking man’s Sarah Palin. A Yale and University of Chicago Law grad, she is quick with a “Fargo”-accented quip. She’s burnished her liberal bona fides by becoming a reliably lefty voice, just last week teaming up with Mr. Sanders to debate health care on prime-time CNN against the most recent Republican senators trying to repeal Obamacare, Lindsey Graham and Bill Cassidy. But not that lefty. She hasn’t signed on to Medicare for All and, on CNN, spoke in favor of a bipartisan approach. What’s more, her voting record from 10 years in the Senate — including, most recently her thumbs up to a handful of Mr. Trump’s cabinet nominees — will cling to her like barnacles.

Kamala Harris, a freshman California senator, has become a liberal rock star with her tough questioning of Jeff Sessions and other Trump administration officials during Senate hearings. It’s her record as California attorney general, her previous job, that could trip her up: She declined to prosecute OneWest, the bank once headed by Treasury Secretary Steven Mnuchin, for alleged foreclosure violations. Still, Ms. Harris seems the most promising of this group — not least because she has less of a voting record her opponents can use against her.

THE CLINTONITE

“Clinton” is almost as much of a dirty word as “establishment.” But one candidate would proudly carry the banner of Clintonism.

Terry McAuliffe, who’ll finish his term as Virginia governor early next year, is an unapologetic friend and backer of both Clintons. He’s a famously fabulous fund-raiser and he has put together a solidly (and surprisingly) progressive record in the commonwealth — tightening gun control laws and reinstituting voting rights for more than 150,000 felons. His national stature grew during the Charlottesville protests, when he provided the sort of moral leadership so sorely lacking from the White House. “Governor Macker,” as he’s known, was once considered a punch line, so laugh at the notion of a President Macker at your own risk.

THE OBAMANAUT

Hillary Clinton tried — and failed — to run for Barack Obama’s third term. Deval Patrick, the former Massachusetts governor, might have better luck. He’d have the unambivalent backing of much of the Obama political machine, including, it is said, Mr. Obama himself. He’s one of the few Democrats out there with Mr. Obama’s rhetorical skills and a life story to match — rising from a Chicago housing project to Harvard and Harvard Law. To be sure, Mr. Patrick’s post-office employer, Bain Capital, would dog him. But if any Democrat is capable of rebuilding the formidable Obama coalition, it’s him.

THE COMEDIAN

Al Franken put his vaunted sense of humor in the deep freeze his first eight years in the Senate to establish himself as a “serious” person. But now he’s letting it back out — “I like Ted Cruz more than most of my other colleagues like Ted Cruz,” Mr. Franken writes in his new book, “and I hate Ted Cruz” — and not a moment too soon for his fellow Democrats. Although he’s a thoughtful wonk, it’s his wit that has some Democrats salivating at the prospect of his appearing on a debate stage opposite Mr. Trump.

THE MILLENNIAL WHISPERERS

Millennials are expected to surpass baby boomers as the largest generation of eligible voters in 2020. So it would only make sense for a few politicians who might still get carded to run themselves.

Seth Moulton, a Massachusetts congressman, is a charismatic, intelligent Iraq war veteran who isn’t afraid to call out party elders like Nancy Pelosi. He’s only 38, and it’s almost certainly too soon for him to have much of a chance at winning the nomination in 2020, but it doesn’t hurt to put his name into the 2020 veepstakes.

At 44, Representative Tim Ryan of Ohio doesn’t make the cut of being a millennial himself, but he’s fashioned himself as a fresh face on Capitol Hill and he thinks he has an economics-focused message for members of that generation, especially those who live in working-class cities like his hometown near Youngstown.

Christopher Murphy, a 44-year-old Connecticut senator, is casting his message at a different segment of millennials — those who live on Twitter, where he offers running political commentary, or listen to podcasts like “Pod Save America,” where he’s made several appearances. His and Mr. Ryan’s campaign slogans write themselves: “You’re Only as Old as You Feel.”

THE COWBOY GOVERNORS

Some Democrats will be tempted to look beyond the Beltway for a savior. Thus the appeal of a certain type of pragmatic governor.

John Hickenlooper, in his second term as Colorado governor, has built a solid economic record there while also instituting tough gun control laws and (despite his objections) overseeing the smooth introduction of legalized marijuana. He’s also evinced a willingness for bipartisanship that has served him well in purple Colorado. He’s an offbeat enough character that it’s possible to see him catching fire.

Steve Bullock is a second-term governor in deep-red Montana, and he’d cast himself as someone who’d help Democrats broaden their electoral map beyond the coasts. It’s not a bad sales pitch. But Mr. Bullock isn’t much of a salesman. One joke making the rounds about him goes that if you close your eyes while he’s speaking, you hear Evan Bayh.

The Mayors

It’s a long step from the mayor’s office to the White House, but with so few Democratic governors — and with the party’s strength in urban areas — it seems an opportune time for a Democratic mayor to take it.

Eric Garcetti, in his second term as Los Angeles mayor, is considered by many Democrats to be a top political talent. And while a run for Congress or the governor’s office might be more realistic, his articulation of an urban agenda, with a focus on infrastructure and immigration, could strike a chord in a presidential race.

Mitch Landrieu, who’ll finish his term-limited tenure as New Orleans mayor early next year, struck a chord in May when he gave a speech explaining why the city was taking down its four Confederate monuments. In the wake of Charlottesville, his words have become even more resonant.

THE BILLIONAIRES

Suffice it to say, the events of 2016 were enough to make any billionaire think a run for the White House was suddenly plausible. And even if Facebook’s political troubles have made a Mark Zuckerberg candidacy a non-starter, 2020 is drawing the interest of a range of other rich people.

Mark Cuban, the outspoken owner of the N.B.A.’s Dallas Mavericks, is the most similar to Mr. Trump, right down to his starring role on a reality-TV show. Howard Schultz, the founder of Starbucks, cuts a less bombastic figure, frequently denouncing partisanship.

But it’s hard to see any billionaire, even one as rabble-rousing as Mr. Cuban, faring well in a Democratic primary in 2020.

THE REPLICAS

David Axelrod, Mr. Obama’s political guru, likes to say that voters usually seek “the remedy, not the replica” of the incumbent. When you consider how much political logic has been turned on its head, perhaps Democrats will nominate a Trumpian figure of their own. Enter the Rock, who inspired the formation of a political action committee to support his presidential aspirations after he announced his intention to run for the White House (albeit in a skit on “Saturday Night Live”).