By Paul Krugman – The New York Times.

A couple of months ago, Jeb Bush (remember him?) posted a photo of his monogrammed handgun to Twitter, with the caption “America.” Bill de Blasio, New York’s mayor, responded with a picture of an immense pastrami sandwich, also captioned “America.” Advantage de Blasio, if you ask me.

Let me now somewhat ruin the joke by talking about the subtext. Mr. Bush’s post was an awkward attempt to tap into the common Republican theme that only certain people — white, gun-owning, rural or small-town citizens — embody the true spirit of the nation. It’s a theme most famously espoused by Sarah Palin, who told small-town Southerners that they represented the “real America.” You see the same thing when Ted Cruz sneers at “New York values.”

Mr. de Blasio’s riposte, celebrating a characteristically New York delicacy, was a declaration that we’re also Americans — that everyone counts. And that, surely, is the vision of America that should prevail.

Which is why it’s disturbing to see Palinesque attempts to delegitimize large groups of voters surfacing among some Democrats.

Quite a few people seem confused about the current state of the Democratic nomination race. But the essentials are simple: Hillary Clinton has a large lead in both pledged delegates and the popular vote so far. (In Democratic primaries, delegate allocation is roughly proportional to votes.) If you ask how that’s possible — Bernie Sanders just won seven states in a row! — you need to realize that those seven states have a combined population of about 20 million. Meanwhile, Florida alone also has about 20 million people — and Mrs. Clinton won it by a 30-point margin.

To overtake her, Mr. Sanders would have to win the remaining contests by an average 13-point margin, a number that will almost surely go up after the New York primary, even if he does much better than current polls suggest. That’s not impossible, but it’s highly unlikely.

So the Sanders campaign is arguing that superdelegates — the people, mainly party insiders, not selected through primaries and caucuses who get to serve as delegates under Democratic nomination rules — should give him the nomination even if he loses the popular vote. In case you’re rubbing your eyes: Yes, not long ago many Sanders supporters were fulminating about how Hillary was going to steal the nomination by having superdelegates put her over the top despite losing the primaries. Now the Sanders strategy is to win by doing exactly that.

But how can the campaign make the case that the party should defy the apparent will of its voters? By insisting that many of those voters shouldn’t count. Over the past week, Mr. Sanders has declared that Mrs. Clinton leads only because she has won in the “Deep South,” which is a “pretty conservative part of the country.” The tally so far, he says, “distorts reality” because it contains so many Southern states.

As it happens, this isn’t true — the calendar, which front-loaded some states very favorable to Mr. Sanders, hasn’t been a big factor in the race. Also, swing-state Florida isn’t the Deep South. But never mind. The big problem with this argument should be obvious. Mrs. Clinton didn’t win big in the South on the strength of conservative voters; she won by getting an overwhelming majority of black voters. This puts a different spin on things, doesn’t it?

Is it possible that Mr. Sanders doesn’t know this, that he imagines that Mrs. Clinton is riding a wave of support from old-fashioned Confederate-flag-waving Dixiecrats, as opposed to, let’s be blunt, the descendants of slaves? Maybe. He is not, as you may have noticed, a details guy.

It’s more likely, however, that he’s being deliberately misleading — and that his effort to delegitimize a big part of the Democratic electorate is a cynical ploy.

Who’s the target of this ploy? Not the superdelegates, surely. Think about it: Can you imagine Democratic Party insiders deciding to deny the nomination to the candidate who won the most votes, on the grounds that African-American voters don’t count as much as whites?

No, claims that Clinton wins in the South should be discounted are really aimed at misleading Sanders supporters, giving them an unrealistic view of the chances that their favorite can still win — and thereby keeping the flow of money and volunteers coming.

Just to be clear, I’m not saying that Mr. Sanders should drop out. He has the right to keep campaigning, in the hope either of pulling off huge upsets in the remaining primaries or of having influence at the convention. But trying to keep his campaign going by misleading his supporters is not O.K. And sneering at millions of voters is truly beyond the pale, especially for a progressive.

Remember the pastrami principle: We’re all real Americans. And African-Americans are very definitely real Democrats, deserving respect.