MEGAN MCARDLE: The Democrats’ Immigration Problem(s).

Briefly: Democratic arguments about immigration mostly aren’t arguments. The party has relied on opposing Trump’s more outrageously exaggerated claims about the criminality and all-around character flaws of immigrants. That’s fine, as far as it goes — but as November showed, it doesn’t go far enough.

The core problem is that Democrats didn’t really make an affirmative argument for an overhaul to U.S. immigration policy that might appeal to voters. Instead, they talked a lot about what great people immigrants are, and how much they benefit from migration. Unfortunately, the clearest group of beneficiaries from this policy — people who want to migrate, but haven’t yet gotten a green card — can’t vote.

Of course there are spillover benefits to immigration, but they are somewhat nebulous compared to the direct benefit to the would-be migrants. It’s easy to explain how immigrants benefit from an open door. Explanations of how the rest of us benefit tend to rely on the trivial or on abstract economic arguments that most people don’t find particularly intuitive or convincing. Those arguments look even more suspicious because they are generally made by the one group that visibly does benefit from a lot of low-skilled immigration, which provides the nannies, lawn-care, and food services that high-skilled professionals rely on to allow them to work longer hours. . . .

Distrust of strangers is a universal human phenomenon, tapping into some pretty deep evolutionary instincts. Once those instincts are aroused, you need very powerful emotional arguments as to why it’s worth taking the risk. “They’re really nice people” is not it. Nor is “It will be great for them” or “Look at this regression analysis.”

Democrats seem to appreciate that this is a problem. You saw this at the convention, where the hours before 6 p.m. — when most people weren’t watching — were heavy on praise for immigration and appearances by illegal immigrants who spoke movingly of their plight. But at the hour when the nation turned its eyes to the television, the paeans in favor of illegal migrants became dramatically more restrained.

Yet instead of solving this problem, Democrats opted to mostly speak in vague generalities and to avoid concrete questions: What percentage of our society should be foreign born? How should we choose the people we allow to migrate? Instead of formulating a clear policy, they relied on institutional inertia and lax enforcement to swell the foreign-born population to nearly 15 percent of the country. And Republicans, whose donor class likes generous immigration rules, were happy to go along.

That was fine as long as those groups were in charge of the status quo. Once Trump took over, however, that became infeasible.

Well, to be fair, Trump took over in no small part because a lot of voters wanted to make that infeasible.

FLASHBACK: Bill Clinton warns of “the large number of illegal aliens” coming into America, and explains his crackdown.

When I posted this earlier, a reader commented: “Donald Trump should televise this Bill Clinton speech from 1995 and then simply state ‘I’m Donald Trump and I approve this message.'”