Sen. Bernie Sanders isn’t quite ready to retire to his lakeside dacha and so once again is running for the presidential nomination of a party to which he doesn’t belong with an agenda about which he can’t be entirely honest.

Go to BernieSanders.com, and you will find a swag store and a donations link but precious little about what the candidate believes. Sanders has been around long enough to appreciate that Democratic presidential campaigns are made of rage and money, with ideas way back there somewhere near the caboose.

To the very limited extent that Sanders is a man of ideas, he is — not that he’d ever admit it — a man of President Trump’s ideas.

Who does this sound like? “I don’t know why we need millions of people to be coming into this country as guest workers who will work for lower wages than American workers.”

Trump? Yes, indeed, but it is Sanders. Rep. Steve King of Iowa and other immigration restrictionists have praised Sanders for his beady-eyed, zero-sum view of immigration.

Sanders has, in fact, been all too happy to appropriate the rhetorical scheme of the alt-right knuckleheads (remember those guys?), denouncing those who take a more liberal view of immigration as advocates of “open borders” — a position held by approximately zero figures in American public life — and agents of a sinister conspiracy advanced by the Koch brothers and affiliated business interests. Which is to say: Sanders’ criticism of the Koch brothers comes from the same direction as Trump’s.

Like his populist fellow travelers, including Trump, Sanders applies much of the same zero-sum thinking to trade. Quiz question: Who described the Trans-Pacific Partnership as a “disaster” — Trump or Sanders?

Both, actually.

Right-wing populists and left-wing populists may disagree about such world-changing issues as whether the phrase “a man with ovaries” actually means anything, but on the fundamental policy questions, they come down strikingly close to one another.

That is because the enemy of populism isn’t the left or the right but liberalism, understood here not in the demented sense we use it in US politics but in its proper sense, the classical-liberal regime of property rights, free enterprise, free trade, individual rights and ­ordered liberty emphasizing ­cooperation among nations.

Sanders, like Trump, is an anti-liberal — and, fundamentally, a nationalist. Sanders may be deep-dipped and tie-dyed in 1970s countercultural horsepucky, but he is a practitioner of a very old and established kind of politics that would have been familiar to such frankly nationalist politicians as Franklin Roosevelt (and Teddy Roosevelt, for that matter), Woodrow Wilson and Benito Mussolini.

Sanders has been shamed out of the blunt, Trumpish way he talked about immigration during those 2016 union hall speeches, but his worldview remains ­essentially the same. Most politicians don’t evolve very much at his advanced age.

The feature of nationalism that Trump and Sanders — and, to a considerable degree, figures such as Sen. Elizabeth Warren and Rep. Alexandria Ocasio-Cortez — are rehabilitating is, in part, corporatism, a word that all of them certainly would abjure and that none of them quite understands.

Contemporary progressives use the word corporatism to describe a situation in which the notionally democratic character of government is subverted by private business interests, but in reality it means something closer to the opposite: the subordination of private business interests to the “national interest.”

Warren, in particular, frequently speaks of the social role of American businesses in explicitly corporatist terms, but the far-left American intellectuals who dream of “workers’ councils” and grand industrial projects directed by the central government are practitioners of classical corporatism, whether they understand the fact or not. The so-called Green New Deal is a textbook corporatist boondoggle.

Sanders may call himself a ­socialist, but then, so did Mussolini, for a long time.

If you view the economy as a kind of national household (which is what the Greek root of “economy” literally means), then Sanders-ism — including his ­restrictionist immigration views, however muffled they now are — makes perfect sense: Why take on responsibility for a bunch of shiftless strangers you don’t really need?

If you take a more intelligent view — well, then you probably aren’t taking Sanders’ campaign very seriously. The good news is that he probably isn’t, either.

Kevin Williamson is the roving correspondent for National ­Review, from which this column was adapted.