The Nazi analogy has long been recognized as the crudest and dumbest form of argument, but it’s enjoying a renaissance.

Former CIA Director Michael Hayden notoriously and unapologetically tweeted a photo of Auschwitz-Birkenau as a response to family separations at the border. Upon a report that parents at the border were being told that their children were being taken to get bathed and disappearing, Chris Hayes of MSNBC tweeted, “What does this remind you of?” Soledad O’Brien chimed in, “Welp, I guess we’ve put to rest the question: ‘Nazi Germany: Could it happen here in America?’ ”

Progressives imagine that they are protecting our system when making these and related charges, but they are really losing faith in it themselves and undermining its legitimacy.

Kumail Nanjiani, a comedian and actor with more than 2 million followers on Twitter, objected to President Trump’s contention that illegal immigration brings criminals into the United States. He said Hitler “focused on crimes by Jews,” and this is what brought on Nazi Germany over time.

Actually, Hitler was named chancellor in January 1933 and immediately acted to curtail press and individual rights and begin repressing the Jews. He used the Reichstag fire to mobilize against opponents, including through violence, and gained full dictatorial powers via the Enabling Act in March 1933.

By comparison, Trump in his first year and a half in office has tweeted, called the press names and — yes — highlighted crimes committed by illegal immigrants. Unpresidential? Yes. Disturbing? At times. Fascistic? No.

Several books, including one by former Secretary of State Madeleine Albright, are devoted to more sophisticated versions of the Trump-as-budding-fascist theme.

In “How Democracies Die,” Steven Levitsky and Daniel Ziblatt write that “Trump’s first year in office followed a familiar script. Like Alberto Fujimori, Hugo Chavez and Recep Tayyip Erdogan, America’s new president began his tenure by launching blistering rhetorical attacks on his opponents.”

Well, yeah, and these comparisons would be fair and apt if Trump went on to purge and jail his opponents.

Levitsky and Ziblatt believe the best scenario for democracy is that Trump loses. A much darker future is that “a pro-Trump GOP would retain the presidency, both houses of Congress, and the vast majority of statehouses, and it would eventually gain a solid majority in the Supreme Court.”

To do all this, Republicans would have . . . to win elections, an odd thing for an anti-democratic party to do.

Yes, authoritarians overseas win elections — by rigging them and disqualifying opponents.

After continuing to win sweeping electoral mandates, per Levitsky and Ziblatt, Republicans would then enshrine their rule by “using the techniques of constitutional hardball to manufacture durable white electoral majorities.”

They’d do this through large-scale deportations (never mind that illegal immigrants don’t vote); immigration restriction (which would require Congress passing laws and would presumably change the foreign-born percentage of the electorate only slowly over time); purges of the voter rolls (if the Ohio example recently upheld by the Supreme Court is any indication, this would involve the removal of nonvoters who didn’t reply to a notice over a period of years) and strict voter ID laws (i.e., requiring a valid ID).

You can object to every single one of these measures and still realize that they hardly amount to the agenda of Erdogan or Fujimori.

The worries about Trump as fascist dovetail with critiques of our system itself as undemocratic. These will become more prominent as Trump moves to almost certainly nominate another robustly constitutionalist, highly credentialed jurist to the highest court in the land.

For progressives like Jonathan Chait of New York magazine and Michelle Goldberg of the New York Times, this is another sign of “minority rule.”

But Republicans get to nominate and confirm Supreme Court justices because they won the presidency and retained control of the Senate in 2016 in a hard-fought national election.

It is true that Trump won despite losing the popular vote, but the Electoral College is nothing new or untoward. It can’t be that Democrats, thought not long ago to have a lock on the presidency, suddenly can’t possibly muster 270 electoral votes. Have Wisconsin, Michigan and Pennsylvania gone from blue wall to unwinnable that quickly? And the Senate, held by Democrats as recently as 2014, become an insuperable electoral obstacle?

Our system will presumably look much better to progressives if Democrats go out and win some elections. You know, like the alleged fascists do.

Twitter: @RichLowry