So many Democrats are running for president that the chair of the National Governors Association, the mayor of America’s largest city and the senior senator from Colorado may not even qualify for the first debate — even though it allows for 20 candidates.

With Montana Gov. Steve Bullock having announced his candidacy Tuesday and New York Mayor Bill de Blasio expected to follow soon, the Democratic field will swell to 23, enough for two football teams, with one left over to play referee.

Some Democratic leaders worry privately that this army of candidates makes it harder for the party to coalesce around a single standard-bearer, and deliver a clear message, in time to mount the strongest possible campaign against a president they urgently want to defeat. And for the candidates, the landscape makes it increasingly difficult to strategize, stand out and make their case.

With the general election still 18 months away, President Trump has already started to throw jabs at his 2020 Democratic rivals. (The Washington Post)

Fourteen of the candidates polled below 2 percent in the last CNN national poll, and for undecided primary voters, the blizzard of “historic” campaign announcements and “sweeping” policy rollouts has been dizzying.

For the campaigns themselves, the emotions range from to fury to desperation to resignation.

“It’s a traffic jam in Iowa and New Hampshire,” said Craig Hughes, a senior adviser to Sen. Michael F. Bennet (Colo.), “especially for those running who currently serve in Congress, putting weekend travel at a premium.”

An historically large field was expected, given President Trump’s perceived vulnerability and the churn within the Democratic Party. But few believed it would be quite this sprawling, and the candidates are being forced to retool their strategies in response.

The usual plan of most campaigns — to connect directly with voters in Iowa coffee shops, New Hampshire diners and the like — has come under pressure as candidates face the reality of overwhelmed and saturated electorates who are far from making a final choice.

“Competition for attention and oxygen is more intensive than anyone could have imagined,” said a top adviser to one of the campaigns, who like others spoke on the condition of anonymity to discuss the struggle. “You don’t have a situation like Trump with the Republicans in 2015, where one candidate is getting all of the attention. You have a lot of candidates who command attention.”

That Republican field, at 17, was seen as enormously unwieldy, making debates cumbersome and ballots confusing. The Democratic field will have at least a half-dozen more than that, and could grow further.

The current candidates are experimenting with different tactics. Former Texas congressman Beto O’Rourke, who boasts of holding the most campaign events in the most places, is doing national television interviews after initially resisting them.

Sen. Kamala D. Harris (Calif.) is upping her attacks on Trump, switching from a less direct approach. Washington Gov. Jay Inslee, Sen. Elizabeth Warren (Mass.) and Sen. Bernie Sanders (I-Vt.) have been taking shots at former vice president Joe Biden, who leads in early polls, partly to get headlines.

And everyone from former housing secretary Julián Castro to Sen. Cory Booker (N.J.) is banking on policy announcements to get attention.

“He’s comfortable where he is now and he anticipates being in a peak position in the fall when it matters,” said Jennifer Fiore, a senior adviser to Castro’s campaign.

Yet the field retains a shapeless, unpredictable feel, its contours shifting and its dynamics fluid. One sought-after prize — a breakout moment, such as a poignant exchange with a voter, that can go viral and rake in donations and attention — has so far been elusive.

The struggle is prompting many campaigns to complain that they’re being treated unfairly and not getting the spotlight they deserve.

Supporters of Sen. Kirstin Gillibrand (N.Y.) note that she has drawn more attention for her morning workout than for her ability to break into conversational Mandarin Chinese on the campaign trail, even as South Bend Mayor Pete Buttigieg received weeks of accolades for his bursts of Spanish, French, Norwegian and American Sign Language.

Other campaigns have found themselves arguing with news organizations that are not able to send reporters to all the campaign events for more than 20 candidates in the early primary states of Iowa, New Hampshire, Nevada and South Carolina.

“When you look at the polls and look at the coverage of candidates like Gillibrand and Castro, there is clear favoritism going on, because the level of coverage given to them is not indicative of their public support,” said one person working on the campaign of former Maryland congressman John Delaney, who has one of the most extensive early-state operations.

Several of the 11 campaign operatives contacted spoke privately with dismay about their negotiations with CNN, as they push to get more than one town hall or a better booking time. Some also complain about Fox News’s decision to shut out candidates who aren’t polling well from its own hour-long sessions with candidates.

And several described the debate qualification rules set by the Democratic National Committee as “ridiculous,” “arbitrary” or “bizarre.” The first debate is scheduled for June 26 and 27, and some of the lesser-known candidates hope it will provide a breakout moment for them, even as the number of candidates onstage makes that harder.

To qualify for the Democratic debate, a candidate must show at least 1 percent support in multiple public polls or attract 65,000 unique donors from at least 20 states. That offers no built-in advantage for party seniority or electoral accomplishment, but it does provide a penalty for joining the campaign late.

Bullock, for example, is not certain to make the debate stage despite his leadership of the National Governors Association. The same is true for de Blasio and Bennet, who temporarily left the campaign trail to recover from prostate cancer surgery, which he says was successful.

The challenge for Marianne Williamson, who writes and lectures on spiritual topics and has already reached the 65,000-donor threshold, has been to persuade public pollsters on the approved party list to put her as an option in their surveys.

“What is hard is name recognition at this point, because name recognition runs the polling part of the DNC rules,” said Patricia Ewing, an adviser to Williamson. “It’s been an active effort to actually be mentioned in the polls.”

The candidates must submit evidence by June 13 that they’ve met the criteria for the first debate. The event will be held on two consecutive nights, each featuring a randomized collection of 10 candidates. A similar debate will be held about a month later, with a July 17 deadline to qualify.

Bullock said Tuesday it was worth completing the Montana legislative session before announcing his candidacy — “I signed my last bill yesterday” — even if he now has less than a month to meet the target for the first debate.

“As long as you’ll put in all of your stories, I’ll hit the donor numbers for sure,” Bullock told reporters. “I’ve got about a month to do that. I hope to do it. But either way, I’m going to be out talking to folks about what we’ve been able to do here.”

He will continue campaigning if he misses the cut, he said.

“I sure hope I make the debate stage; I think everybody does,” Bullock said. “I think that, candidly, the debate stage would be lacking a bit if they didn’t have somebody that actually got reelected in a state where Donald Trump won. It would be lacking if it didn’t have someone who bridged the divides in a majority-Republican legislature to get things done.”

The third debate comes in September, and the campaigns expect the requirements to rise at that point, in terms of both polling and donations. That could begin culling the herd.

Democratic National Committee Chairman Tom Perez has not said whether he plans to cut the debates to one night and 10 candidates before the Iowa caucuses in February, but one limitation may be whether networks are willing to devote two consecutive nights in prime time to the events.

The first two debates have been awarded to MSNBC and CNN, cable networks that are more willing to scramble their prime-time lineups, but the party later may want to broaden its reach by partnering with broadcast networks.

Meanwhile, the candidates have little option but to continue the daily grind of the campaign, hoping that at some point the crowd thins and that they are left standing, having raised enough money to keep going and registered enough in the polls to keep getting covered.

“It is impossible to be able to predict what the world of February 2020 will look like in May of 2019,” said Ari Rabin-Havt, chief of staff to the Sanders campaign. “Candidates should be doing the things they have to do to run winning campaigns — putting out ideas, getting themselves media, raising money and building field programs.”

Lisa Gardinier, a librarian at the University of Iowa, was in the audience when Biden held a rally there recently. He was the sixth candidate she’d seen in person, she said, after Booker, Harris, Buttigieg, Castro and Warren.

Looking toward next year’s Iowa caucuses, she hoped for diversity in the party’s leadership. “When it comes time to caucus, I can see that there are so many good candidates of color that I can’t really see myself backing a white candidate right now,” she said. “There are so many good options that I’m going to go for one of those first.”

But in this field, that means she’ll have at least six candidates to choose from.

David Weigel, Dan Balz, Jenna Johnson and Chelsea Janes contributed to this report.