You should never let your opponents define you, because they’re not looking to do you any favors. That’s why Republicans, especially those who voted for President Trump, should object to being called populists.

Populism was one of the nastiest of American political movements. It was inevitable, therefore, that Trump would be called a populist. But that doesn’t describe Trump, or the Republican Party he re-invented.

It’s true that, like most populists, Trump thinks that tariff walls that keep foreign goods out of the country might help American workers. But then Abraham Lincoln and William McKinley thought so, too, and they weren’t populists.

It’s also true that, like most populists, Trump championed an underclass unjustly held back by an aristocracy of wealth. But then Karl Marx and socialist Eugene V. Debs thought the same thing, and they weren’t populists. And like most populists, Trump decried the influence of money in politics. But then so did Hillary Clinton and Liz Warren, and nobody called them populists.

Here’s what the accusation of populism really means. It’s a smear meant to link one to people like “Pitchfork Ben” Tillman, one of the vilest characters in American political history. Tillman was the governor of South Carolina from 1890 to 1894 and served as the state’s representative in the US Senate for the next 23 years. He invented Jim Crow laws in his state, defended lynch mobs and boasted of the African-Americans he had killed.

Trump is something new in American politics. He’s not Andrew Jackson, or a plain-speaking Harry Truman. He’s not Ronald Reagan. He’s unlike anything we’ve seen before, for the simple reason that he’s up against something we’ve never seen before: a left that’s given up on the American dream of a mobile and classless society, that defends economic immobility and aristocracy.

Trump isn’t a populist. He’s a conservative nationalist. As a conservative he favors socially conservative institutions and free-market solutions to political questions. As a nationalist he is middle of the road or liberal when it comes to taking care of Americans who have fallen behind, through a generous safety net.

That might sound like an unnatural union of opposites, but similar parties have had a long history in our sister parliamentary governments. Benjamin Disraeli was another conservative nationalist. As a parliamentarian, he opposed Sir Robert Peel’s free-trade policies and in the process created a new Tory party.

And a year before Friedrich Engels shocked readers with his description of the wretchedness of East End London in “The Condition of the Working Class in England” (1845), Disraeli had written no less passionately about economic inequality.

Then, as the Conservative prime minister, Disraeli extended the franchise to all adult male heads of households in the 1867 Reform Bill.

In a speech on the bill, Disraeli described what he thought the Tory Party should be, in terms that also define Trump’s Republican Worker’s Party:

“I have always considered that the Tory party was the national party of England . . . It is formed of all classes, from the highest to the most homely, and it upholds a series of institutions that are in theory, and ought to be in practice, an embodiment of the national requirements and the security of the national rights.”

As a nationalist, Disraeli and his party wanted all Britons to prosper. He could never have called one group of his countrymen deplorable, or ignored half the voters because they were in the wrong identity group.

By reaching out to all Britons, he took the Whig’s issues away from them, just as Trump did in dishing the Democrats.

Not much has changed, and the American who wishes to understand the shape of things to come might do well to read up on the “Tory Democracy” of Lord Randolph Churchill (Winston’s father) or observe the similarities between Trump’s agenda and the National Policy of Sir John A. Macdonald’s Tory Party in Canada.

They were conservative, but because they supported generous social-welfare policies they were sometimes called Red Tories. And they’re the ancestors of Trump’s Republican Party.

F.H. Buckley teaches at Scalia Law School and is author of the forthcoming “The Republic of Virtue: How We Tried to Ban Corruption, Failed, and What We Can Do About It.”