Only white candidates have qualified for next week’s Democratic presidential debate, the first time in this election cycle that no minority contender will make the stage. It’s a dynamic that critics say threatens to undercut the party’s rhetoric of inclusivity.

The race for the 2020 Democratic nomination kicked off last year with a historically diverse pool of candidates, including two black senators, a black mayor, a Hispanic former Cabinet secretary and an Asian businessman. Since then, all have either dropped out or failed to qualify for a spot on the stage, determined by poll numbers and donations.

Now the specter of an all-white debate in the mostly white state of Iowa is prompting concern among party activists.

“Both the way the primary is set up and the way debates are done are a problem,” said Rashad Robinson, executive director of Color of Change, a racial justice organization. “The system they have designed has suppressed the most loyal base of the Democratic Party.”

He added: “Anyone with an understanding of civil rights law understands how the rules can be set up to benefit some communities. The Democratic Party should look at the impact of these rules and question the results.”

The Democratic Party has held six debates so far, with the seventh scheduled for Tuesday. The party will host at least five additional debates in 2020.

Candidates qualify based on public polling and the number of small donors they attract. Over time, those standards have risen, winnowing the field.

For Tuesday’s debate at Drake University in Des Moines, candidates must show contributions from 225,000 unique donors and reach 7 percent support in two polls of early states, or 5 percent in at least four polls of early states and national surveys.

The latest survey, released hours before Friday’s midnight cutoff, showed the four top candidates clustered in the lead. The poll, sponsored by the Des Moines Register, CNN and Mediacom, showed Sen. Bernie Sanders (I-Vt.) attracting 20 percent of the vote; Sen. Elizabeth Warren garnering 17 percent, Pete Buttigieg at 16 percent and former vice president Joe Biden with 15 percent.

Nobody else achieved more than 10 percent in a poll with a margin of error of 3.7 percentage points.

The whiteness of the debate stage — and the top candidates — has been an issue for weeks. During the last debate, businessman Andrew Yang called it “an honor and disappointment” to be the only person of color included.

Sen. Cory Booker (D-N.J.) told the Associated Press this week that he had one of his best fundraising days during the December debate, even though he wasn’t on the stage, because of the “reaction of the absence of me, and frankly, people with more diverse lived experiences.”

The Democratic National Committee, which runs the debates, has defended its rules, saying the requirements were set well in advance and that the stage reflects the preferences of voters, including voters of color.

“We’ve set forth a clear set of transparent, inclusive rules,” DNC chairman Tom Perez said this week in an interview with MSNBC, adding: “We set those rules out in advance. And it’s for the voters to decide.”

The responsibility for increasing diversity lays with the voters, he said.

“If you want to make sure that a candidate of color makes the debate stage, when a pollster calls you, make sure you make that preference felt,” Perez said. “Because that is how you move the polling needle and, again, the voters are the ones who are making these decisions.”

He also noted that Sen. Kamala D. Harris (D-Calif.), who is black, would have qualified for the debate in December and probably January as well. She dropped out of the race early last month amid flagging fundraising.

But critics believe the party isn’t being introspective enough.

“The fact that they are defending the process and saying it is fair is troublesome,” Robinson said. “At this point, I don’t know what they can do to disrupt the rules. But let’s at least be honest about the result.”

The all-white stage reflects long-held societal biases among voters, said Aimee Allison, executive director of She the People, an organization that elevates women of color in politics.

She argued that the conversation this year around “electability,” a top concern among many, highlights how entrenched these ideas are.

“It’s a troubling indication of the built-in bias toward white men and white candidates over everyone else,” Allison said. “There is a deep cultural belief that hasn’t been adequately challenged.”

“Why are we assuming that a Biden” — who tops polls of black voters — “is a stronger candidate?” Allison added. “What is magic now? He was beaten by a younger African American candidate” in 2008, when Biden garnered just one percent of the vote in the Iowa caucuses before dropping out.

Two white women — Sens. Elizabeth Warren (D-Mass.) and Amy Klobuchar (D-Minn.) — have qualified for the January debate. Rep. Tulsi Gabbard (D-Hawaii) remains in the race, though she didn’t qualify. Self-help guru Marianne Williamson dropped out of the contest Friday and wouldn’t have been on the stage.

The men on the stage will be Biden, Buttigieg, Sanders and billionaire businessman Tom Steyer.

The DNC has not unveiled its rules for the subsequent debates this year and hasn’t said whether it will continue to include a small-donor qualification. Removing that hurdle could provide billionaire and former New York Mayor Mike Bloomberg a chance to make the debate stage. He is self-funding his campaign and isn’t accepting any donations, so he cannot make the debates under the current framework.

The change would do little to boost minority candidates. Booker and Yang both met the donor threshold for January’s debate, but neither polled high enough to qualify.

Some longtime observers said the whiteness of Tuesday’s debate shouldn’t overwhelm the reality that the Democratic Party is friendly to minorities.

“Yes, the optics will be off-putting to some observers — a bad thing for a party that will need the enthusiastic support of all sectors of its coalition,” said Randall Kennedy, a Harvard Law professor who has written extensively on race. “But it is mistaken to suggest that the racial cast of the lineup means that the Democratic Party is hostile or indifferent to people of color. We need to look beneath and beyond looks.”

But the absence of nonwhite candidates can limit the discussion of issues that are important to minorities.

“Where do the candidates stand on fully restoring the Voting Rights Act? On racial gerrymandering?” said Rev. William J. Barber II, the co-chair of the Poor People’s Campaign, a group focused on ending systemic racism and poverty. “It’s not just who is on the stage. It is what we choose to debate on the stage.”

Barber plans to fly to Iowa next week to urge the candidates to speak more about poverty.

He also wanted to know how the DNC set its debate qualifications. “Who is in the room when the rules are made? And why are they made in such a way that could created this lack of diversity?” he asked.

He also pushed major minority groups to advocate for change, suggesting that the Congressional Black Caucus and Congressional Hispanic Caucus should pull their endorsements until the debate stage reflects the country.

“We have to be sure we put in front of America the issues that are important to American and a picture that looks like America,” he said.