Speaking at a press conference alongside the president of Mexico and the prime minister of Canada, President Barack Obama offered a strong implicit rebuke to Donald Trump, saying, "I’m not prepared to concede the notion that some of the rhetoric that’s been popping up is populist."

Obama didn’t mention Trump by name, but at the end of the joint appearance he did go off on what he himself described as a "rant" about an unnamed figure who "engaged in rhetoric about how we’re going to look after ourselves and take it to the other guy," and insisted "that’s not the definition of populism."

Instead, Obama said that he is the true populist. "I care about workers being able to have a collective voice in the workplace and get their fair share of the pie," he said. "I want to make sure that kids get a decent education."

By contrast, an unnamed "someone else who has never shown any regard for workers" and "has never fought on behalf of social justice issues" and "in fact has worked against economic opportunities for workers and ordinary people" doesn’t "suddenly become a populist because they say something controversial in order to win votes."

Instead, Obama said, "That’s nativism or xenophobia. Or worse. Or it’s just cynicism. So I would just advise everyone to be careful about suddenly attributing to whoever pops up at a time of economic anxiety the label that they’re populist."

Obama’s challenge to the press is to ask would-be populists about their record: "Where have they been? Have they been on the front lines working for ordinary people?"

This is a theme you can expect Democrats to return to time and again in the months to come, looking in detail at Trump University and Trump’s casinos to ask whether Trump has ever really stood for the interests of ordinary people, or whether he’s just deploying populist rhetoric as a self-interested ploy.

The political science that predicted Trump's rise