In a blow to their hopes of making the debate stage next month, billionaire Tom Steyer, Sen. Kirsten Gillibrand of New York and a number of other presidential candidates missed a chance to advance in a new poll on Monday, just two days before the cutoff.

Ten candidates have already qualified for the ABC-sponsored Democratic debate in Houston in September, but Steyer, Gillibrand, Rep. Tulsi Gabbard of Hawaii and author Marianne Williamson were hoping some last-minute surveys would push them across the threshold.

Now they'll have to hope that new polls come out before Wednesday — a tall order, especially considering that pollsters often avoid surveying Americans in August, when many people are on vacation.

Candidates need four polls showing them at 2 percent or higher and 130,000 unique donors.

Gabbard, D-Hawaii, needs two more qualifying polls; Gillibrand needs three more polls, plus more donors. Williamson has enough contributors, but needs three more polls. For the four polls to qualify, they have to be conducted by DNC-approved pollsters, be from a combination of different pollsters and conducted in different geographic areas, such as Iowa, New Hampshire, or the entire nation.

Steyer is just one poll away. But a new Monmouth national survey out Monday was a setback — it pegged his support below 1 percent.

The poll also found a three-way tie for first place between Vermont Sen. Bernie Sanders, Massachusetts Sen. Elizabeth Warren — both at 20 percent — and former Vice President Joe Biden at 19 percent, down from 32 percent in the pollster's last survey.

"The main takeaway from this poll is that the Democratic race has become volatile. Liberal voters are starting to cast about for a candidate they can identify with. Moderate voters, who have been paying less attention, seem to be expressing doubts about Biden," said Patrick Murray, director of the independent Monmouth University Polling Institute. "But they are swinging more toward one of the left-leaning contenders with high name recognition rather than toward a lesser known candidate who might be more in line with them politically."

Steyer, a billionaire activist, has spent heavily on TV ads since entering the race this summer, helping to raise his name recognition to 70 percent, according to Monmouth. But that has not made him popular: Just 9 percent have a favorable impression of Steyer, compared with 25 percent who view him unfavorably.

Steyer and other low-polling candidates slammed the Democratic National Committee over the debate rules last week during a DNC meeting in San Francisco.

"The American people deserve to hear this message in September, but are being denied by the lack of recent qualifying polls," Steyer campaign manager Heather Hargreaves said in a statement. "We are calling on the DNC to expand their polling criteria to include more qualifying polling."

His campaign also has a petition going calling on the DNC to add surveys of Nevada, one of the four early primary and caucus states, to its list of qualified polls.

Wednesday deadline approaching: There have been NO DNC debate-qualifying polls in Nevada in nearly a month. Your voice matters, but it’s not being heard -- voters like you in Nevada should get a say before the deadline on Wednesday. Add your name. — Tom Steyer (@TomSteyer) August 26, 2019

Sen. Michael Bennet of Colorado, who has little hope of making the debate stage, was even more critical, using his speech to the DNC to say the party's rules were “stifling debate at a time when we need it most."

Other candidates who remain far off from qualifying include New York City Mayor Bill de Blasio, Montana Gov. Steve Bullock, former Maryland Rep. John Delaney and Ohio Rep. Tim Ryan.

Candidates who miss the September debate will still have a chance to qualify for the October debate when the thresholds will be the same, but they'll have more time. The standards are expected to rise in November for future debates, however.

If any more candidates qualify for next month's contest, the debate will once again be spread across two nights, like the June and July debates, since the maximum number of candidates on stage is 10.

The 10 candidates who have qualified already include: Biden; Warren; Sanders; New Jersey Sen. Cory Booker; Mayor Pete Buttigieg of South Bend, Indiana; former Housing Secretary Julián Castro; California Sen. Kamala Harris; Minnesota Sen. Amy Klobuchar; former Texas Rep. Beto O'Rourke; and entrepreneur Andrew Yang.