Harris remains an important candidate because the Democratic field remains flawed. And if you see Trump as a threat to America’s interests — which he is — you should at this point be rooting for as many strong potential nominees as possible. (That’s why I’d also welcome for a surge from one or two of the candidates way down in the polls.)

Why do I think the field is flawed? Because Biden — who really does have swing-voter appeal — doesn’t look sharp right now. Sanders looks sharper, but his democratic socialism is a bigger general-election risk than the Bernie faithful acknowledge.

Warren is running by far the best campaign, with a clear message that echoes the most consistently successful Democratic strategy of the last century: populism. Yet she still hasn’t shown enough instinct for appealing to the voters who swung from Obama to Trump and back to the Democrats in the 2018 midterms. Those voters don’t want their private health insurance taken from them.

In the weeks ahead, I think Harris has two main jobs. First, she and her top advisers should be honest with themselves about her surprising penchant for mistakes. On Medicare policy, she has twice had to explain that she didn’t mean what she sure seemed to mean. On a radio show, she made a flippant remark about marijuana and Jamaica that her own father, who’s a Jamaican immigrant, criticized. At a town hall, she laughed when a voter used a slur for the mentally disabled (to describe Trump’s agenda), and she later claimed that she hadn’t heard the words.

There is a pattern here. Harris can be too quick to speak or react without thinking. It’s an understandable problem, because running for president is devilishly hard. But the way to get better at it — as past winners have done — is to avoid excuses and be ruthlessly (albeit privately) self-critical.

Her second task is to develop a clearer theory of her campaign’s case. Obama’s was about hope and change. Warren wants to fight for the middle class. Harris stands for … what, exactly? It’s not always evident, not from her vaguely titled book, “The Truths We Hold,” and not from her stump speech.

When asked about this problem in a recent interview, Harris rejected the poetry of campaigns and said, “I come at issues through the lens of how it actually impacts people.” That’s not good enough. It doesn’t help voters understand her values and priorities.