© Greg Nash Sen. Cory Booker is struggling to meet the qualifications for the December Democratic debate.

Sen. Cory Booker (D-N.J.) on Thursday delivered an impassioned address about the dwindling number of candidates of color in the Democratic primary, warning that voters were not getting a fair opportunity to choose from a diverse group of candidates.

"It's a problem that caucus-goers here in Iowa and in Nevada and voters in South Carolina and New Hampshire are being denied the choices that they are telling us they want in February," Booker said at a campaign event in Iowa.

Booker noted that Democrats needed a diverse coalition in order to defeat President Trump.

"And this is not just about individual candidates — it's about the diverse coalition we need to defeat Donald Trump," he said.

Booker has denounced the dwindling number of candidates of color in the Democratic primary, pointing specifically to Sen. Kamala Harris's (D-Calif.) recent exit from the race.

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"It's a damn shame, frankly, that Kamala Harris's voice is no longer in this race," Booker told BuzzFeed News's "AM to DM."

"I've seen the bile, the anger, from my family members, to people in the Congressional Black Caucus, to leaders of color across this country who just don't understand how we've gotten to a point now where there's more billionaires in the 2020 race than there are black people," he continued.

Six candidates, including billionaire Tom Steyer, have qualified for the December debates, all of which are white.

Booker, himself, has struggled to meet the qualifications to be on the December debate stage.

The senator needs to reach two Democratic National Committee benchmarks by Dec. 12: Over 200,000 unique campaign donors and four polls showing him with the support of at least 4 percent of voters in order to qualify for the forum.