The White House on Monday blocked the entry of several categories of foreign workers in a new presidential proclamation that will extend through the end of 2020. The measures also expand President Trump’s April 22 executive order denying green cards to applicants in several immigrant visa categories.

Trump administration officials also piled on new regulatory changes for asylum seekers and proposed changes to the H-1B visa category used by U.S. companies — particularly in the technology sector — to bring in highly skilled workers.

The administration defended its moves as an effort to help U.S. workers facing the worst unemployment crisis since the 1930s. But the moves also use executive powers to impose the kind of immigration restrictions that Trump adviser Stephen Miller and other hard-liners have been promoting for years.

Q: Which visa categories are barred by Trump’s new decree?

A: The new proclamation, which took effect immediately on Monday, denies entry to the United States to four major “nonimmigrant” visa categories: H-1B, L, J and H-2B, with the exception of workers in the “food supply chain.”

Q: What about temporary workers who are already in the United States? Do they have to leave?

A: No. The restrictions apply only to workers attempting to enter the United States using one of those visas.

Q: The U.S. Chamber of Commerce and several trade industry groups were sharply critical of the restrictions and say the measures will hurt economic recovery. Why? What types of jobs do those temporary workers fill in the United States?

A: Some of the loudest objections have come from the technology sector, which has long relied on the H-1B visa category for highly skilled workers such as software engineers and programmers. The United States issued about 188,000 H-1B visas last year, according to State Department data, and companies say those workers are crucial to their competitiveness.

The L visas, also now suspended, are used mostly for intracompany transfers, providing flexibility to large global companies that want to move executives within their companies. This allows a company like Boeing, for example, to bring a European or Asian executive for a job at one of the firm’s U.S. offices. Last year the State Department issued almost 77,000 L1 visas, along with a similar number for their immediate family members.

Companies use H-2B visas to fill seasonal and short-term positions, but the companies have to first demonstrate that they attempted to hire U.S. workers and were unable to. This category was increasing under Trump when the unemployment rate was low before the pandemic, and last year the government awarded nearly 98,000 of these visas.

Trump’s new proclamation will make an exception for H-2B workers in the food service industry, where such workers sometimes fill positions as crab-pickers and cannery workers. The H-2A visa category for agricultural labor is not subject to Trump’s restrictions.

Finally, the restrictions on J visas for “cultural exchange” workers will freeze out those coming as interns, trainees, teachers, camp counselors and participants in summer work travel programs.

Q: What about “au pairs”?

A: A senior administration official who briefed reporters Monday initially said the child-care providers who travel to the United States as “au pairs” — about 20,000 per year — would be “excluded.” When the text of the proclamation was released two hours later, it showed that au pairs will have no exemption and will also be denied entry.

Two senior administration officials said applicants who can demonstrate that the entry of their child-care provider is in the U.S. “national interest” can receive an exemption.

Q: What about the immigrant visa categories Trump suspended in April?

A: The president’s April 22 executive order — which he promoted as an “immigration ban” — has sharply reduced green card eligibility. U.S. citizens seeking to bring in their spouses or minor children can still do so, but most other categories for family reunification or employment-based green cards are suspended. The White House has extended those restrictions through the end of 2020 with Trump’s new proclamation.

Q: What is the immediate impact of these measures? I thought global travel was mostly shut down anyway because of the coronavirus.

A: The pandemic has crippled global travel and sharply reduced visa processing at U.S. consulates abroad, so gauging the real impact of the restrictions is difficult. In February, the State Department issued about 640,000 nonimmigrant visas to temporary workers, tourists and other visitors. Last month, the number fell to 40,000 — a 94 percent decline.

Q: What other changes is the Trump administration making?

A: Trump administration officials laid out several other long-term changes they’re planning to make to the work visa programs like H-1B. The administration wants to replace the current visa system, which awards visas to companies that apply through a lottery, with a new model based on salary.

Under that system, H-1B visas, which have an annual cap, will be given to the companies willing to pay the highest salaries for those positions. Trump officials said this will encourage firms to fill lower-level jobs with U.S. workers, while ensuring that foreign employees are brought in to occupy highly specialized roles.

Trump administration officials have not indicated whether they plan to pursue the changes via regulation or some other executive action, so it’s unclear if and when the measures could take effect.

Q: What about the new work restrictions for asylum seekers?

A: Amid the flurry of other changes, the administration Monday also made it much more difficult for immigrants with pending asylum claims to obtain work authorization. They will now have to wait a full year to gain eligibility.

In the past, immigrants seeking asylum in the United States typically were granted work authorization quickly so that they could support themselves financially while waiting for U.S. immigration courts to process their cases.

Trump administration officials have argued that work authorization has become a magnet for economic migrants who file false or meritless asylum claims, knowing it will probably take years for courts to rule on their cases because of a lengthy backlog.

The administration has not said how it expects asylum seekers to survive in the United States without the ability to work legally, and it has ushered in penalties to deny asylum protections to applicants who arrive without legal authorization.

Q: Will this order affect President Trump’s own businesses?

A: It appears so. Two of Trump’s properties — the Mar-a-Lago Club in Palm Beach, Fla. and a golf club in Jupiter, Fla. — use guest-worker visas to hire cooks, housekeepers and waiters. Last year, Mar-a-Lago asked to hire 80 foreign workers for the winter busy season. But a senior administration official said Tuesday that hospitality businesses like these will be subject to the new restrictions.

Trump’s order does still allow businesses to apply for an exemption, for workers whose entry would be “in the national interest.” Trump’s company could apply for that exemption if it wanted. The company did not respond to questions on Tuesday.

David Fahrenthold contributed to this report.