Chair of the Democratic National Committee, Tom Perez, speaks before a Democratic presidential primary debate, Wednesday, Nov…
Chair of the Democratic National Committee, Tom Perez, speaks before a Democratic presidential primary debate, Nov. 20, 2019, in Atlanta.

WASHINGTON - The head of the Democratic Party, Tom Perez, insists the party is committed to diversity even though Tuesday night's presidential debate in Iowa will be the first all-white debate of the 2020 campaign.

Since the last Democratic showdown in December,  Senator Cory Booker of New Jersey, an African American, and Latino candidate Julian Castro — the former mayor of San Antonio and federal housing secretary — dropped out of the race for the Democratic nomination to challenge U.S. President Donald Trump in November..

Among the remaining candidates, Asian-American entrepreneur Andrew Yang; Congresswoman Tulsi Gabbard of Hawaii, a Samoan American; and the black former governor of Massachusetts, Deval Patrick, did not qualify for Tuesday's face-off only weeks before the Iowa Caucuses.

All three failed to meet the criteria set up by the party. They include polling at least 5% in four polls and raising funds from at least 225,000 individual donors.

A CNN employee stands on the stage, Jan. 14, 2020, before a Democratic presidential primary debate hosted by CNN and the Des Moines Register in Des Moines, Iowa.

Despite the lack of brown skin and Asian features on Tuesday night's stage, Perez — the chair of the Democratic National Committee — told CNN he is "proud" that the 2020 campaign featured "the most diverse field in American history, including women, African-Americans, and the first openly-gay Democratic candidate, Pete Buttigieg.

Perez said the party "set a remarkably inclusive and frankly low bar throughout the campaign" that allowed such a wide range of candidates to be heard. Twenty Democratic candidates took part in the first debate in June.

"When you look at the issues that are confronting communities of color and you look at who has been fighting for you, the Democratic Party’s long track record of fighting for diversity and inclusion is something I'm very proud of," Perez said.

FILE - Massachusetts Gov. Deval Patrick, center, waves to people in the audience as his wife Diane Bemus, left, looks on at the conclusion of ceremonies for the unveiling of his official state portrait, Jan. 4, 2015, at the Statehouse, in Boston.

The sole African-American Democratic candidate still in the race is Patrick, the ex-governor of Massachusetts. He was a late entree and is polling just about 1% nationally.

Patrick  says all six candidates in Tuesday's debate are "remarkable" public servants, but says "America will not see herself in full" and called the debates a "reality TV episode."

"Instead of helping Democrats to choose our most compelling nominee from a range of diverse talent, the debates have become an end in themselves," he said in a statement posted on twitter.

Tuesday night's lineup includes former vice president Joe Biden; Senators Bernie Sanders of Vermont, Elizabeth Warren of Massachusetts and Amy Klobuchar of Minnesota; former mayor Buttigieg of South Bend, Indiana, and businessman and philanthropist Tom Steyer.

Patrick called many of the debate participants friends. But he said none of them has ever had to "fear for their safety after being pulled over for a routine traffic stop ... questioned about their citizenship ... or been followed by store security."

About 40% of registered voters are regarded as people of color. But none of the 2020 black candidates were able to win much black support, including Patrick, Booker, and Senator Kamala Harris of California who dropped out last month,

The latest polls show that Biden, who was vice president under former U.S. President Barack Obama,  leads among black voters who are likely to vote for a Democrat. Sanders, a progressive independent, trails far behind by about 20 points.

Analysts say name recognition is the main reason for their apparent popularity among African-Americans.