Democrats started this presidential campaign season with more than 20 candidates. Eventually, it dropped to about a dozen, with, so far, only five of those “qualified” to appear on the next debate stage this month.

But debate performance doesn’t seem to matter much. Both U.S. Sen. Kamala Harris and former Obama cabinet member Julián Castro had excellent debate performances, and yet they have dropped out of the race.

It’s a money thing.

With just $9 million in the bank, Sen. Harris said she couldn’t see her way clear to the nomination given her extremely limited resources. Mr. Castro, matching Sen. Harris in grace and reflectiveness, said, “It just wasn’t our time.” He, too, felt he did not have enough money in the bank to compete. It almost certainly would have helped these candidates qualify if they had the resources, say, of former New York Mayor Michael Bloomberg, who pumped $100 million into his campaign in just one month.

In fairness, though, it is es- sential to note that U.S. Sen. Bernie Sanders raised a whop- ping $34.5 million in the fourth quarter of 2019 alone. South Bend, Ind., Mayor Pete Buttigieg and former Vice President Joe Biden raised more than $20 million in that same quarter, and U.S. Sen. Elizabeth Warren came close.

For some candidates, money isn’t the only issue. Did they meet the thresholds the Democratic Party set for debate qualification? Do they and their advisers think they can win? What are the polls saying? So even though U.S. Sen. Kirsten Gillibrand had $14.9 million in the bank when she dropped out of the race last August, she was not polling well and failed to qualify for the September debate.

Meanwhile, U.S. Sen. Cory Booker did not qualify for the last debate, but he is hanging in the contest.

Although Sen. Booker and entrepreneur Andrew Yang are still in the race, the Democratic field is mostly white, and the debate stage on Tuesday, Jan. 14, in Des Moines, Iowa, is likely to be all white. What does that say about progress in this nation? What does it say about the Democratic Party, which presents itself as a big-tent political party that has embraced diversity?

For Democrats, there are three keys to winning this election. First, Dems must engage “new voters,” including young people and first-time voters. Next, they must monitor the rules around elections and scrutinize the ways people are removed from the voting rolls. Finally, and most impor- tantly, Democrats must place significant effort on getting out the vote in November — and during the primaries. New voters and communities of color, especially, must be targeted.

Election protection organizations have the monitoring issue covered, and there are likely to be massive get-out-the-vote efforts led by civil society organizations. But what engages new voters? They must feel that the political process reflects them.

Already Latino voters are concerned that Democrats aren’t vying for their vote. And African-American voters think that the Democratic Party takes them for granted.

To engage new voters, perhaps Democrats need to examine their rules to embrace more candidates of color. And they need to fight for legislation that makes it easier to vote.

Democrats like to call themselves candidates of the “underdog.” But when billionaires like Tom Steyer and Mr. Bloomberg come sauntering through the door, concern for the underdog seems to go out the window.

The writer is an economist, educator and author.