Editor's note: The following editorial originally appeared in The National Review.

Donald Trump leads the polls nationally and in most states in the race for the Republican presidential nomination. There are understandable reasons for his eminence, and he has shown impressive gut-level skill as a campaigner. But he is not deserving of conservative support in the caucuses and primaries. Trump is a philosophically unmoored political opportunist who would trash the broad conservative ideological consensus within the GOP in favor of a free-floating populism with strong-man overtones.

Trump’s political opinions have wobbled all over the lot. The real-estate mogul and reality-TV star has supported abortion, gun control, single-payer health care à la Canada, and punitive taxes on the wealthy. (He and Bernie Sanders have shared more than funky outer-borough accents.) Since declaring his candidacy he has taken a more conservative line, yet there are great gaping holes in it.

His signature issue is concern over immigration — from Latin America but also, after Paris and San Bernardino, from the Middle East. He has exploited the yawning gap between elite opinion in both parties and the public on the issue, and feasted on the discontent over a government that can’t be bothered to enforce its own laws no matter how many times it says it will (President Obama has dispensed even with the pretense). But even on immigration, Trump often makes no sense and can’t be relied upon. A few short years ago, he was criticizing Mitt Romney for having the temerity to propose “self-deportation,” or the entirely reasonable policy of reducing the illegal population through attrition while enforcing the nation’s laws. Now, Trump is a hawk’s hawk.

He pledges to build a wall along the southern border and to make Mexico pay for it. We need more fencing at the border, but the promise to make Mexico pay for it is silly bluster. Trump says he will put a big door in his beautiful wall, an implicit endorsement of the dismayingly conventional view that current levels of legal immigration are fine. Trump seems unaware that a major contribution of his own written immigration plan is to question the economic impact of legal immigration and to call for reform of the H-1B–visa program. Indeed, in one Republican debate he clearly had no idea what’s in that plan and advocated increased legal immigration, which is completely at odds with it. These are not the meanderings of someone with well-informed, deeply held views on the topic.

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