WASHINGTON – The first Democratic primary debate of the year will also be the smallest — and the least diverse.

Tuesday’s debate, hosted by CNN and the Des Moines Register, is being held at Drake University in Des Moines, Iowa, at 9 p.m. ET. It is the last primary Democratic debate before the Iowa caucuses on Feb. 3.

This month's debate qualifications required candidates to have at least 225,000 individual donations. In addition, candidates needed to get 5% in at least four national or early-voting state polls, or at least 7% in two early-voting state polls, which include Iowa, New Hampshire, Nevada and South Carolina. Candidates had until the end of the day Friday to meet them

Only six candidates out of the 13 Democrats running made it to the debate stage:

The debate qualification thresholds have previously been criticized by some candidates who didn't make the cut, including Sen. Cory Booker of New Jersey and entrepreneur Andrew Yang. Yang last month called on the Democratic National Committee to commission polls in an effort to increase the diversity of participants in the upcoming debate. The DNC declined.

Steyer looked like he would miss the stage but qualified Thursday, the day before the deadline, after two Fox News state polls, one for Nevada and the other for South Carolina, were released. Steyer was in double digits in both states after heavily investing in advertising in both.

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Who didn't make the debate stage?

Although the 2020 Democratic field continues to winnow — Marianne Williamson ended her campaign Thursday — there were still several candidates who won't be on Tuesday's debate stage.

No candidates of color made it to the debate stage, including Booker, Yang, Rep. Tulsi Gabbard of Hawaii and former Massachusetts Gov. Deval Patrick.

Yang was the only non-white candidate who was close to making it to the stage, but still needed three polls to qualify. He also was the only non-white candidate on the December debate stage.

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Other candidates who didn't make the debate stage include Sen. Michael Bennet, former New York City Mayor Michael Bloomberg and former Rep. John Delaney.

The next debate is on Feb. 7 at Saint Anselm College’s Sullivan Arena in New Hampshire, just four days before the New Hampshire primary.