The Democratic National Committee is upsetting some of its own — including those running for president in 2020.

Driving the news: The DNC's new threshold to qualify for the September debates doubles the requirements to take part. They had always said the rules would change for future debates, but hadn't released the specifics until earlier this week.

The big picture: This is just the latest example of how the national party and candidates are trying to navigate the unruly primary field in 2020.

A number of candidates (like Colorado Sen. Michael Bennet and Massachusetts Rep. Seth Moulton, for example) have yet to qualify for the debates at all. Eight have qualified just through polling.

Eleven have qualified via polling and donations, but the DNC won't announce who has officially made the first debate stage until next month.

Why it matters: There are 24 Democrats running to replace Donald Trump as president. That number cannot possibly be sustained. And some worry that drastically changing the rules will severely winnow the primary field — particularly for minority candidates.

What they're saying: "The role of the DNC shouldn’t be to narrow the field; that’s the role of the voters. It’s like we learned nothing from 2016," said Michael Starr Hopkins, John Delaney's national press secretary.

Delaney sent a letter to DNC Chairman Tom Perez asking how the new threshold was decided. "Arguably, one of the most important gate-keeping functions is the determination of the nominee, and Democratic voters deserve transparency about how this is conducted," he told Axios.

"One of the most troubling things about this donor threshold is that it treats digital fundraising as a tactic rather than as a strategic advantage Democrats have," said Jess Morales Rocketto, a strategist and former digital organizing director for Hillary Clinton's 2016 campaign. "It encourages irresponsible spending and may ultimately undermine our diversity commitments."

The DNC told Axios that the change is "consistent with history" and they always change the threshold as the primaries get closer.

"I question whether or not people who have real digital fundraising experience have been involved in this process," Rocketto added.

Sayu Bhojwani, founder of the nonpartisan political organization New American Leaders, said in a statement: "The DNC’s new rules, coming so early in the cycle, will amplify the harm done to diverse candidates by a political elite — from pollsters to talking heads — dominated by white male gatekeepers."

"It fatigues donors, has a disparate impact on candidates with diverse supporters, and rewards institutional advantages like email lists, staff and campaign accounts," said one Democratic operative who's talked with various campaigns.

The other side: Adrienne Elrod, a Democratic strategist who served as director of strategic communications on Clinton's campaign, says candidates should invest heavily in the DNC because they'll be focused on organizing in battleground states for the general election before the nominee is selected.

"Because we have to take on Trump, we have to determine the nominee and switch to the general. We can’t start preparing for the general election in July 2020 — we have to start organizing for that now."

The DNC told Axios that for the first time this cycle, presidential candidates are raising money directly for the national party and holding fundraisers for them.

Go deeper: Liberal activists drive the Democratic Party