The Democratic Party often promotes itself as America’s political party that champions diversity. But a growing number of those on the left — including some presidential candidates — argue that that needs to be better reflected in the primary process.

Former housing secretary Julián Castro of Texas, one of the most ethnically diverse states in the country, recently called for changing the order of the primaries.

“We do need to change the order of the states, because I don’t believe that we’re the same country we were in 1972,” he said. “That’s when Iowa first held its caucus first. And by the time we have the next presidential election in 2024, it would have been more than 50 years since 1972. Our country has changed a lot in those 50 years. The Democratic Party has changed a lot.”

Castro praised Iowans for being deeply engaged in the political process but said the state — which is more than 90 percent white — is not representative of the Democratic Party or America.

Castro made his comments from Iowa, a state where he has only received 1 percent support in the most recent Monmouth University poll. Pete Buttigieg, the South Bend, Ind., mayor, is leading in Iowa, despite repeatedly making headlines for his relatively dismal support from black voters, according to the most recent poll.

Castro isn’t an outlier in his belief that the lack of diversity in Iowa’s caucus process leaves some voices out. Conversations about changing the primary order surfaced during the last presidential election campaign because of precisely that concern.

LGBT activist Charlotte Clymer argued that Castro is correct and that a state that better reflects the diversity of America should go precede Iowa.

“I have enormous respect for my fellow Americans in Iowa and New Hampshire, but two overwhelmingly white states shaping a race to decide who will lead a nation that is not overwhelming white does not strike me as reflective of a healthy democratic process,” she tweeted.

Activists in the Democratic base have long argued for a change in the primary system. Candidates often determine whether they will keep pursuing the White House, in part, based on their Iowa performance. But that is months before the first primary — South Carolina — that features a significant number of voters of color.

Many Iowans also believe that the current caucus process leaves out some demographics in the state and support changing to a primary system that could lead to greater diversity among participants. According to a new Des Moines Register-CNN-Mediacom Iowa poll, 44 percent of Iowa’s likely Democratic caucusgoers said it is more important for Iowa to hold a primary “so everyone can vote, even if it means Iowa would no longer” be first.

Some argue that the current caucus system — a long process that happens at night — often excludes people with disabilities, elderly people, working-class voters who work at nights and single parents with child-care needs.

But the argument for keeping Iowa first is that the voters are deeply engaged and accessible. Campaigns without much money or manpower get to take advantage of Iowa’s grass-roots culture to make their case to Americans who are deeply invested in the election.

David Redlawsk, co-author of “Why Iowa? How Caucuses and Sequential Elections Improve the Presidential Nominating Process,” previously told The Fix during the last presidential election: “Iowa may not be perfectly representative [of the United States], but no one state is.”

The political science professor added: “It actually makes more sense in a sequential system not to worry about the ‘representativeness’ of any one state. Combined, the first four carve-out states — Iowa, New Hampshire, South Carolina and Nevada — do a pretty good job of representing the constituencies and issues that drive American politics.”

Even former vice president Joe Biden, the candidate leading in some national polls with black and Latino voters, acknowledged that the electorates in New Hampshire and Iowa are significantly different from the rest of the country.

“Are they representative historically and practically — based on race and creed and color — of the nation? No, they’re not,” he said. “But that doesn’t mean they shouldn’t play a major part.”

When asked if the order of the primaries should change, Biden replied, “No” — even though he ended his 2008 presidential bid after a poor Iowa performance.

“They are first. That’s what they are now. It’s not going to change,” he said. “It is what it is.”

But the idea that something should be because it has always been may not continue to be a winning argument for members of a Democratic base who are increasingly concerned that they aren’t as valued as they should be, especially since people of color make up a growing percentage of the Democratic Party and the left.

Although Castro is not faring much better with people of color than he is performing overall, concerns that a candidate could move forward without significant support from people of color could become more widespread. If members of the base continue to feel ignored or taken for granted, pushback against the status quo will likely intensify until some change is made.