They are thinking. Weighing. Mulling. And, in some cases, already campaigning.

It can feel like half the Democratic Party is considering a White House run. In fact, it’s only a couple dozen. Below, an accounting of how the prospective contenders have been preparing.

RUNNING

— Julián Castro, 44

Former housing secretary; former mayor of San Antonio

“I’m running for president because it’s time for new leadership. Because it’s time for new energy.”

Opted out of challenging Sen. Ted Cruz, R-Texas, for the Senate in the 2018 midterm elections.

Once a rising political star, has struggled to find a role during the Trump administration.

Money could be an issue, especially if former Rep. Beto O’Rourke, D-Texas, a small donor magnet, also mounts a bid.

Signature issues: Has emphasized a platform of universal prekindergarten, “Medicare for all” and immigration reform.

— John Delaney, 55

Former congressman from Maryland; former businessman

“I think I’m the right person for the job, but not enough people knew who I was or still know who I am.”

Was elected to the House in 2012 as a “pragmatic idealist,” in his telling.

Has been running aggressively since 2017.

Has already visited every county in Iowa, though it’s unclear if he has improved his long-shot prospects.

Signature issues: Has pitched himself as a bipartisan problem-solver, but has also endorsed liberal causes such as universal health care.

— Tulsi Gabbard, 37

Congresswoman from Hawaii; Army National Guard veteran

“There are a lot of challenges that are facing the American people that I’m concerned about and that I want to help solve.”

Supported Bernie Sanders in the 2016 primaries.

Has drawn condemnation for meeting with Syria’s president, Bashar Assad, whose regime has been accused of using chemical weapons against civilians.

Has apologized for her history of anti-gay statements and her past work for an anti-gay advocacy group.

Signature issue: Opposition to U.S. military intervention overseas, including in countries like Syria.

— Kirsten Gillibrand, 52

Senator from New York; former congresswoman

“I’m going to run for president of the United States because, as a young mom, I am going to fight for other people’s kids as hard as I would fight for my own.”

Was once a congresswoman from a conservative House district (with policy positions to match).

Has transformed herself into a progressive champion in President Donald Trump’s Washington, becoming one of the Senate’s leading liberal voices.

Signature issue: Has long placed women’s equality and opportunity at the center of her policy agenda.

— Kamala Harris, 54

Senator from California; former attorney general of California; former San Francisco district attorney

“I believe our country wants and needs some leadership that provides a vision of the country in which everyone could see themselves.”

Would bring a star power and history-making potential to the race that few other Democrats can match.

One of few new Democrats to join the Senate after 2016.

Quickly drew notice for her tough questioning of Trump’s cabinet nominees — and later, his Supreme Court nominee, Brett Kavanaugh.

Signature issues: Unveiled middle-class tax cut legislation in fall and has championed a liberal civil-rights agenda in the Senate.

— Richard Ojeda, 48

Former West Virginia state senator; military veteran

“We’re going to have quite a few lifetime politicians that are going to throw their hat in the ring, but I guarantee you there’s going to be a hell of a lot more of them than there are people like myself.”

Made his name in West Virginia politics as one of the leading voices in the teacher protests that roiled the state Capitol in 2018.

Ran a populist House campaign in fall, but lost in a heavily pro-Trump district.

Signature issue: Wants to return the party to its populist roots and lessen the influence of powerful financial interests.

— Elizabeth Warren, 69

Senator from Massachusetts; former Harvard professor

“It’s time for women to go to Washington and fix our broken government, and that includes a woman at the top.”

Has done some of the most extensive preparations for a presidential run.

Attempted to dispatch questions about her Native American heritage by releasing the results of a DNA test.

That effort raised questions about her readiness for a national bid.

Signature issues: Income inequality and what she sees as a middle class under attack from big corporations and political corruption.

— Andrew Yang, 44

Former tech executive who heads an economic development nonprofit

“Universal basic income is an old idea, but it’s an old idea that right now is uniquely relevant because of what we’re experiencing in society.”

Is running a long-shot campaign on a proposal to establish a universal basic income funded by the government.

Has drawn some media attention for highlighting tech issues like robotics and artificial intelligence.

Signature issue: Establishing a universal basic income of $1,000 per month for all Americans.

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ALL BUT CERTAIN

— Cory Booker, 49

Senator from New Jersey; former mayor of Newark

“What we need now are courageous actors who call to the conscience of our country a higher moral imagination, who call for a revival of civic grace.”

Would be one of the most gifted orators in the field, likely running on a politics of uplift that recalls former President Barack Obama’s 2008 campaign.

Enjoys a vast fundraising base, thanks to long-standing connections to donors around the country.

Signature issues: Has been one of the leaders in the Senate on criminal justice reform, but his appeal would likely center on his call to unify the country.

— John Hickenlooper, 66

Former governor of Colorado; former mayor of Denver

“We’re beyond mulling. I think we’re engaging people I’ve known and trusted and understand some of the subtleties around running for the highest office.”

A political moderate with a record of success in a purple state.

A former geologist who struck it rich when he opened a brewery in Denver.

Will likely cast himself as someone who can attract support for a broad coalition, though some of his victories entailed cutting deals with the Republican business establishment.

Signature issues:Has stressed his record of consensus-building around issues like expanding Medicaid, gay rights and gun control.

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LIKELY TO RUN

— Joe Biden, 76

Former vice president; former senator from Delaware

“I think I’m the most qualified person in the country to be president.”

Has run for president twice before.

Is among the best-liked figures in the Democratic Party, known for his down-to-earth personality and his ability to connect with working-class voters.

Regards 2020 as his last chance to run for president.

Signature issues: Restoring America’s standing on the global stage; strengthening economic protections for low-income workers in industries like manufacturing and fast food.

— Steve Bullock, 52

Governor of Montana; former state attorney general

“I do have a story of how I’ve been able to bring people together, and I think that’s in part what our country desperately needs.”

Democratic governor of a state that Trump won easily in 2016.

Would offer himself as a bridge to rural America.

Came out in favor of an assault weapons ban, despite overseeing a state that prizes its hunting.

Signature issues: Expected to make campaign finance reform central, while also pushing early childhood education and other policies aimed at reducing economic inequality.

— Eric Garcetti, 47

Mayor of Los Angeles; former City Council president

“It’s going to be about national unity; it’s going to be about winning the future.”

Passed up a chance to run for governor of California in 2018.

Has positioned himself as a pragmatist with concrete accomplishments on issues like infrastructure and mass transit.

If elected, would be the first mayor to be elevated directly to the Oval Office.

Signature issues: Has emphasized his record of achieving left-of-center policy consensus on matters like transportation, taxes and infrastructure.

— Bernie Sanders, 77

Independent Senator from Vermont; former congressman

“If it turns out that I am the best candidate to beat Donald Trump, then I will probably run.”

A self-described democratic socialist.

Was the runner-up in the 2016 Democratic primary.

Would begin a second White House race with a more extensive organization-in-waiting than any other candidate.

Might face difficulties retaining the same level of support he enjoyed in what was effectively a head-to-head race against Hillary Clinton.

Signature issues: Will likely run on “Medicare for All,” free college tuition and curtailing the influence of, as he calls them, “the billionaires.”

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MIGHT RUN

— Michael Bloomberg, 76

Billionaire media executive; former mayor of New York City

“I do think that after 12 years in City Hall ... that I have a lot of experience, which would be useful if I was president of the United States.”

Has flirted with mounting a bid for president for more than a decade.

Re-registered as a Democrat in October, nearly two decades after he left the party to run for mayor as a Republican.

Has voiced stark disagreements with progressives on issues including bank regulation, stop-and-frisk police tactics and the #MeToo movement.

— Sherrod Brown, 66

Senator from Ohio; former congressman

“We’re seriously thinking about it, we’re seriously talking about it.”

A rare Ohio Democrat who found success in a once-purple state shading red.

Could make the case that his fiery economic populism and liberal record are a compelling fit for a party that needs to reassemble a coalition of Midwestern states that Trump flipped in 2016.

Is a fierce Trump critic on effectively every issue but one: trade.

— Jay Inslee, 67

Governor of Washington; former congressman

“It is absolutely imperative that the Democratic Party put forth a candidate who will make climate change a principal, front-burner issue.”

A two-term governor known for his environmental policies.

Has become one of the party’s most forceful climate advocates, calling on Democrats to embrace a green-energy jobs program.

Has also left the door open to running for a third term as governor, since Washington does not have term limits.

— Amy Klobuchar, 58

Senator from Minnesota; former Hennepin County, Minnesota, attorney

“This is the moment for the Midwest, and we don’t want to be forgotten again in a national election.”

Became a hero to many Democrats for her stern, cool questioning of Kavanaugh during his confirmation hearings.

Has called for Democrats to focus on reclaiming the swing states in the middle of the country.

Has acknowledged she is considering a campaign for president, but does not appear poised to enter the race immediately.

— Mitch Landrieu, 58

Former mayor of New Orleans; former lieutenant governor of Louisiana

“Probably not, but if I change my mind, you’re going to be the first to know.” (Landrieu’s response when asked if he was running.)

Controversial decision to remove his city’s Confederate monuments vaulted him into the national political conversation.

Has drawn considerable attention from Democratic donors and political strategists, and could be a formidable candidate in the South.

Has repeatedly said, in public and private, he is unlikely to run.

— Terry McAuliffe, 61

Former governor of Virginia; former chairman of the Democratic National Committee

“While I haven’t decided whether to be a candidate myself, I will be closely watching our side and working to ensure that the Democratic message is realistic, optimistic and focused on helping all Americans.”

A fixture in Democratic Party politics who became a successful governor.

Would highlight the economic record and social policies he’s championed, which include legalizing same-sex marriage and restoring felon voting rights.

Some around him are unsure whether there’s a road to the presidency for an establishment white male politician with close ties to the Clinton family.

— Jeff Merkley, 62

Senator from Oregon; former speaker of the Oregon House of Representatives

“You would really have to build a vast operation to be competitive ... And so it’s balancing that effort against putting all my efforts in through the Senate.”

Exploded onto the national scene in June 2018 with a viral video showing him being refused entry to a facility in Texas where migrant children were being held.

Was the lone senator to endorse Bernie Sanders in 2016 and is hoping to harness some of that progressive energy.

Democrats in his home state showed little interest in changing an existing law so that he could be on the ballot for both the Senate and the presidency in the same year.

— Beto O’Rourke, 46

Former congressman from Texas

“This smallness, this bigotry, this paranoia, this anxiety — we’ve got to be for the big, aspirational, ambitious things.”

Became a celebrity of Democratic politics in the Trump age, and narrowly lost to Cruz in 2018.

Has delivered a message of national unity and red-state liberalism via constant social media livestream to voters inside and outside of Texas.

Any success in 2020 would draw from this viral appeal, particularly to younger Democrats, and from the small-dollar fundraising army it has earned him.

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UNLIKELY TO RUN

— Michael Bennet, 54

Senator from Colorado

A moderate Democrat known for bipartisanship.

Does not have nearly the national profile of some Senate peers considering a run, but is weighing whether there is room in the field for a less fiery Democrat.

— Hillary Clinton, 71

Former secretary of state; former senator from New York; former first lady; 2016 Democratic presidential nominee

Has refused to publicly rule out mounting a third bid for the presidency.

While some longtime allies quietly push the idea, others close to her say she has little interest in running again.

— Bill de Blasio, 57

Mayor of New York City

Could credibly make the case that he has fused liberal policy feats like universal prekindergarten with falling crime and a sturdy economy.

Past forays into national politics, like a progressive nonprofit and a halting endorsement of Hillary Clinton, have ended in disaster.

— Eric H. Holder Jr., 68

Former attorney general; anti-gerrymandering activist

A career prosecutor who has never run for office before.

Tried his hand at campaigning for fellow Democrats in the midterm elections and appeared to like it, but unclear if he is prepared to actually put his own name on the ballot.

— John Kerry, 75

Former secretary of state; former senator from Massachusetts

The 2004 Democratic nominee and Obama’s chief diplomat.

Author of a recent memoir about his life and, at 75, was thought to be done with politics.

Is deeply upset about the Trump presidency and has indicated he would like to continue to play a role in public life.

— Howard Schultz, 65

Former chief executive of Starbucks

Has long mused about making the jump from the boardroom to politics.

Remains to be seen whether a wealthy executive could find success with Democratic primary voters.

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NOT RUNNING

— Bob Casey, 58

Senator from Pennsylvania

“I have concluded that the best way for me to fight for America ... is to stay in the U.S. Senate and not run for the presidency in 2020.”

— Chris Murphy, 45

Senator from Connecticut; former congressman

“Am I ruling it out? Here we go, I’ll rule it out for you.”

— Deval Patrick, 62

Former governor of Massachusetts

“After a lot of conversation, reflection and prayer, I’ve decided that a 2020 campaign for president is not for me.”

— Tom Steyer, 61

Billionaire former hedge-fund executive; climate change and impeachment activist

“Most people come to Iowa around this time to announce a campaign for president. But I am proud to be here to announce that I will do whatever it takes, for as long as it takes, to remove a president.”

— Oprah Winfrey, 64

Media mogul; former talk show host; philanthropist

“I would not be able to do it. It’s not a clean business. It would kill me.”

This article originally appeared in The New York Times.