A year ago, candidate Donald Trump made immigration a cornerstone of his campaign messaging. Now President Trump’s best proposal on immigration is inadequate and mean-spirited.

We’re not talking about Trump’s dream of building a wall between the United States and Mexico. Sure, the president is threatening to shut down the government if Congress doesn’t come up with money for it. But the wall will never be part of a serious immigration discussion, outside the most xenophobic and bigoted circles, at least as long as there are 41 Democrats in the Senate.

No, this is about Trump’s endorsement of a Senate bill that would cut in half the number of legal immigrants entering the country. In recent years, the federal government has issued about 1 million green cards annually. The bill would reduce that to about 500,000.

The bill also would create a “merit-based” immigration system that prioritizes immigrants with job skills over those with family ties. Immigrants with family ties to legal residents and citizens now receive about two-thirds of green cards.

At best the bill would have no effect on the national economy, wages or jobs. At worst, it would dampen economic growth for decades.

There are, of course, noble principles in favor of immigration. America is a nation of immigrants. We welcome your tired, your poor, your huddled masses yearning to breathe free. We try to keep families together. And we are stronger for having diverse cultures and ideas.

But this isn’t a time of noble principles in the halls of power. Fortunately, dollars and cents, which always have a place in the halls of power, favor immigration, too.

The University of Pennsylvania’s Wharton School conducts nonpartisan economic and budget analyses. When it reviewed the effects of immigration on the U.S. economy, it found that immigration has had little to no impact on long-term wage growth. Meanwhile, it has positively affected federal, state and local budgets, and it leads to greater innovation and a better-educated workforce.

Those findings align with the findings of a far more comprehensive analysis conducted by the National Academies of Sciences, Engineering, and Medicine.

Immigrants take jobs that Americans don’t want, and they often are disproportionately likely to be highly educated innovators who found companies and create jobs.

The Wharton School conducted a separate study of the bill that Trump has endorsed. If it becomes law, in a decade, gross domestic product would be 0.7 percent lower and there would be 1.3 million fewer jobs than without the immigration reduction.

In fairness, the very immigrants denied green cards would have filled most of those lost jobs. But even if that means few Americans lose jobs, what is the gain? Unless one considers punishing the families of legal residents and citizens a worthy goal, there is no upside.

Trump, a Wharton graduate, should listen to his alma mater.

Immigration and guest-worker programs need comprehensive reform, not pernicious cuts. Congress should focus on fixing a guest worker program that even Trump’s own Mar-a-Lago resort is not averse to abusing when hiring laborers. It should look at ways to curb illegal immigration and encourage a robust policy that honors both noble principles and dollars and cents.

Pockets of harm will remain, of course. In rural areas with low-education work forces, immigrants can take jobs from Americans and depress wages somewhat. If Trump wants to help them, he should target training and investment, not undercut a system that balances out or benefits Americans on a national scale.

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