President Donald Trump's handling of the coronavirus crisis has cratered his approval rating. Meanwhile, Americans increasingly think the country is on the wrong track. So what is Trump doing to reverse his political slide? Turning to his old and tired formula of attacking immigration.

He announced during his press briefing yesterday that he will sign an executive order as soon as this evening suspending legal immigration to the country for 60 days. He is billing this move as necessary to protect American jobs and health in the face of the pandemic. But if the few available details of his plan are any indication, it seems that he himself does not believe that line. This is pure political theater that'll upend the lives of immigrants and their American loved ones just so that Trump can virtue signal to his anti-immigration hard-right base ahead of the November elections.

Trump launched his first presidential bid by denouncing Mexicans as "rapists" and "criminals" and pledged to build a "big, beautiful" wall on the southern border. But what began as a slam on unauthorized immigration morphed into an all-out assault on legal immigration as soon as he walked into the White House.

One of his first acts was to ban travel from several predominantly Muslim countries. He also slashed America's refugee program in less than half and is failing to admit even the number he allowed. But these and other moves were just baby steps toward a much more ambitious agenda to slash and radically revamp America's legal immigration program.

He demanded that Congress cut family-based immigration in half in exchange for reinstating the legal status of "Dreamers," which he himself had scrapped. (Dreamers are folks who were brought to this country without authorization as minors, who have grown up as Americans and often have little connection with their birthlands.) But when Congress demurred, he went to town to achieve through administrative means what he couldn't through legislative ones—the kind of thing that Republicans used to vociferously condemn when Trump's predecessor attempted it.

Trump scrapped the Obama-era program handing work authorization to the spouses of foreign techies enduring a decades long wait for their already approved green cards. His "Buy American and Hire American" executive order smothered the high-tech H-1B visa program in red tape, vastly increasing the processing time and doubling the rejection rate. As if that's not enough, he recently implemented something called the public charge rule, which makes it exceedingly difficult for immigrants to upgrade their immigration status—for example, guest worker visas to green cards and green cards to naturalization—if they or their American family members collect or are likely to collect even the smallest amount of some means-tested cash or non-cash public benefits. This, along with other measures, will result in a 30 percent reduction in legal immigration next year, according to a National Foundation for American Policy study.

The coronavirus crisis has been manna from heaven for Trump's restrictionist agenda.

The only visas that were still being entertained at all—albeit at an extremely scaled-back level—were long-term visas for jobs, visas for studying in the United States, and green cards sponsored either by American employers or American family. This long-term program is what Trump's unprecedented executive order is now purportedly going after.

Trump claims that the ban will last 60 days after which he may review and renew it for another 60 or so. But his travel ban was supposed to last 90 days. It is now on day 1,181 and covers even more countries.

It is unclear how far-reaching this new order will be. For example, will it be targeted at new applicants or also those already in the pipeline who may have already paid thousands of dollars in visa and legal fees? Will it apply primarily to those applying for visas overseas or also those who are already here in the United States? If it is the latter, then does that mean that, say, the foreign spouse of an American citizen awaiting a green card will have to return home? What about an H-1B foreign high-skilled immigrant awaiting renewal or a green card? Many of them have been in the country for decades and have American children who may be locked out of their parents' country. Will these families be forced to split, with the parents needing to quit their jobs and return while their children stay in the U.S.?

Trump knows that halting all legal immigration will decimate America's ability to fight the coronavirus. That's because immigrants are disproportionately represented in frontline professions. Immigrants are only 13.7 percent of America's population, but constitute 35.2 percent of the home health care aides, 28.2 percent of physicians, 20.9 percent of nursing assistants, 18.9 percent of health care diagnosing or treating practitioners, 18.5 percent of clinical lab technicians, 15.2 percent of medical assistants, 15 percent of registered nurses and 14.9 percent of health technicians, according to the Cato Institute's David Bier.

Meanwhile, without foreign farm labor, America's domestic food supply chains will come to a grinding halt given just how reliant American agriculture is on it. Indeed, even as Trump reduced every other visa program, last year he certified more than 250,000 H-2A agricultural worker visas—a 10 percent increase from the year before—because Republican lawmakers in red states that tend to be more rural demanded it.

So Trump realizes that undercutting foreign workers in health care and agriculture at this juncture with a full ban will massively undermine America's ability to cope with this pandemic, which is why he has hinted that these categories will be exempted from his executive order.

Meanwhile, given that nearly 40 percent of medical and life scientists and nearly 30 percent of chemists and material scientists are foreign-born—all fields that are racing to find a coronavirus cure or vaccine—Trump says that down the road he might pass a secondary order exempting some of them, too, so that they can keep their H-1Bs.

This will still create massive uncertainty for these folks in the interim. But it'll also leave many categories of immigrants unprotected, including (most likely) international students who cough up exorbitant out-of-state fees that universities will need even more badly given that the pandemic will almost certainly force state governments to cut funding. (Many universities have already announced hiring freezes.)

But the vast exemptions that Trump is planning to carve in the virtual wall he's constructing to seal off America from the world are a tacit admission that immigrants are indispensable for vital sectors of the American economy, not a threat to American jobs.

The purpose of Trump's executive order, then, must be to rally his restrictionist base and ensure that it makes the schlep to the polls this November. It's pure political posturing that'll do not an iota of good for America.