Democrat presidential hopeful Sen. Cory Booker (D-NJ) slammed the upcoming Democrat presidential debate due to its stage’s “lack of diversity.”

Booker’s remarks were made in an email sent to supporters on Friday, the same day as the deadline for qualifications to participate in the next debate, which is likely to feature no people of color.

“Today is the deadline to qualify for the DNC’s January debate,” Booker wrote. “Once again, it’s looking like we’re going to see a debate stage next week that doesn’t reflect the true diversity of our party.”

He continued:

I know I’ve written to you about this topic a few times now — and it pains me to have to do so. But, it is deeply problematic that a Democratic primary field that started as the most diverse in history will almost certainly feature no candidates of color in the next debate. This lack of diversity doesn’t represent the ideals of our party — and it doesn’t represent the ideals of our country.

Booker also criticized the Democratic National Committee for its thresholds to participate in the debates, blaming them for “cutting off access to the debate stage for candidates of color who deserve to be heard in this election.”

Booker said in the email:

The DNC’s debate thresholds have had the effect of cutting off access to the debate stage for candidates of color who deserve to be heard in this election. There have barely been any polls in the field that would allow a campaign like ours to demonstrate momentum and qualify for the debate.

In order to qualify for the January debate, candidates had to bring in at least five percent support in at least four qualified or single-state polls, or at least seven percent in two qualified early-state polls. They also must have received donations from at least 225,000 unique donors, with at least 1,000 of those being in a minimum of 20 states, territories, or the District of Columbia.

“I’m going to keep speaking out about this and forcing our party to have the difficult discussions we need to be having,” he added, before asking for donations to his campaign.”