On Wednesday, President Trump endorsed a bill by Sens. Tom Cotton, R-Ark., and David Perdue, R-Ga., that would dramatically reform the immigration system.

The bill, known as the "Reforming American Immigration for a Strong Economy Act," seeks to halve the number of immigrants granted residency each year from 1 million to 500,000. The RAISE Act would also preference skilled worker immigrants before the family members of current U.S. residents. It would also eliminate a visa diversity system that would have granted 50,000 green cards next year.

Finally, the bill would halve the refugee admittance target-rates from around 100,000 to 50,000.

As I see it, the bill has two positive and two negative components.

The first positive is the RAISE proposal to change the criteria by which residency applications are accepted or rejected. The current U.S. system allows far too many low-skilled immigrants into the country. If we want an economy that is more productive, more creative, and thus better positioned to grow, we need more skilled workers and fewer low-skilled workers.

Preferencing skilled workers isn't just about the economic interests. It's also about reducing government spending. That's because a lower-skilled immigrant is far more likely to require government welfare or Medicaid coverage than is a high-skilled worker who can pay their own bills. By allowing the latter into the country, we boost the economy and protect government spending. By allowing the former, we produce a negligible economic impact alongside higher government spending.

The bill's second positive is its elimination of the visa diversity program. A bureaucratic creation that replicates existing immigration systems, the visa diversity program has no justifiable purpose. Its 50,000 visa slots should be rolled into the high-skills visa program.

Unfortunately, the two other major elements of the RAISE act are less impressive.

For a start, the reduction of refugee visas from 100,000 to 50,000 is arbitrary and capricious. Perhaps 100,000 is too much, but 50,000 is too low. We are a nation that prides itself on the ability to offer salvation to those in need; we should find a median approach that balances security interests with humanitarianism.

Second, assuming we move to a high-skilled visa system, reducing total visas from 1 million to 500,000 makes little sense.

Again, if the central plank of our immigration reform interest is boosting economic growth, more skilled workers is a good thing. We need more scientists, doctors, entrepreneurs, and engineers. Capping how many of these workers we accept means capping our economic potential. This is something Trump, Cotton, and Perdue should recognize.

In addition, as our population ages and our entitlement programs remain un-reformed, younger Americans have significant interest in immigration policies that boost the skilled workforce. After all, the fewer skilled workers we have, the higher taxes existing workers will have to pay to support our elders. In its present form, this legislation is a payoff to older Americans at the expense of younger ones. That's not right.

Ultimately, the RAISE bill has some positives. But it also has too many negatives. The White House, Cotton, and Perdue need to have another look at their legislation.