What does it say about Democrats when all 6 candidates in the Iowa debate are white?

Only six Democrats — all white — are facing off Tuesday, and one of them is likely to take on President Donald Trump in November.

Not an encouraging reality of a presidential primary that began with the most diverse field ever.

What happened to the Democratic Party of diversity and inclusivity? It's ridiculously hilarious to see that the most ethnic candidate on the national stage is Joe Biden.

Julián Castro, the former housing secretary, is out. The most promising African Americans, Sens. Kamala Harris of California and Cory Booker of New Jersey, dropped out of the race long before a single vote is cast.

And the remaining minority, the Asian-American businessman Andrew Yang, didn’t muster enough public support — among other things — to qualify for Tuesday’s debate in Des Moines, Iowa.

Is the system rigged against minorities?

The six contenders who qualified for the last debate before the Feb. 3 caucuses are Biden, former South Bend, Ind., Mayor Pete Buttigieg, billionaire Tom Steyer and Sens. Bernie Sanders, Elizabeth Warren and Amy Klobuchar.

Who’s to blame for the all-white Democratic field on the national stage? Arguably, it’s up to individual contenders to win over voters’ hearts and minds. And minority candidates failed to fire up voters and donors.

But is the system rigged against minorities?

Castro, who never gained more than 2% in national polls and who’s now backing Warren, bitterly complained of media bias and a party primary system that gives predominantly white states, Iowa and New Hampshire, too much early selection power.

“I appreciate how seriously Iowa & New Hampshire take their role as first-in-the-nation,’’ Castro said in a November tweet. “But we’ve changed in the 50 years since order was established — and I believe it’s time our primaries reflect our nation’s diversity.”

Is Castro right or just bitter? He is right, in part. It's a fact that mostly white voters in Iowa and New Hampshire have too much power in the presidential selection process. That may partly explain why Barack Obama, an extraordinarily charismatic man, has been the only person of color to win the presidency in the country's 233-year-history.

Castro, Harris and Booker maybe young and smart politicians but aren't Obama. And thus never picked up momentum even within their own race.

Or do Dems just want to beat Trump?

There are nearly 60 million Latinos in the nation, of which a record 32 million are projected to be eligible to vote in 2020. You’d think Castro would have galvanized Latinos but didn’t. He never gained more than 2% in national polls.

Similarly, an estimated 30 million African Americans are eligible to vote this year, and they’re largely betting on Biden.

A new Washington Post-Ipsos poll shows black Americans favored Biden over any other candidates: 48% of those surveyed support Biden while 20% backed Sanders. The remaining candidates didn’t even come close.

Democrats, minorities included, are fixated with defeating Trump, and to do so they gave up the chance to elect a man or woman of color.

Biden’s popularity with blacks and Latinos stems to some extent from the notion that he’s best equipped to take Trump out. But whoever wins the Democratic nomination will have to truly galvanize minorities.

It won’t be enough for Biden to count on having served as vice president under Barack Obama. And the progressive politics of the other frontrunners won’t be enough to get the Latino and black vote.

Democrats — minorities included — are betting on an all-white party tent where the most ethnic candidate is a 77-year-old guy named Biden. What does that say about the Democratic Party's inclusiveness?

Elvia Díaz is an editorial columnist for The Arizona Republic where this column first appeared. Follow her on Twitter, @elviadiaz1.

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This article originally appeared on Arizona Republic: Democratic debate in Iowa is all white. What happened to diversity?