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WASHINGTON — President Donald Trump signed an executive order Wednesday to "pause" the issuance of green cards for 60 days, describing it as an effort to protect Americans from competition from foreign workers during the coronavirus pandemic.

The order is effectively a restriction on entry that applies to people outside the U.S. seeking lawful permanent residency, which grants people the right to live and work in the U.S. and is a mandatory stepping stone to citizenship for all types of immigrants.

It affects people applying for green cards through employment, family or other means, with some significant exceptions.

The announcement follows a late-night tweet from Trump on Monday that came as a surprise, even to many of his allies, with sweeping language that raised questions about whom it would affect.

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Here are some of the key questions and the answers.

Who's affected?

The order temporarily prohibits people outside the U.S. as of its signing from getting green cards.

A major category of people who are banned is those seeking green cards though a family member of an American — a parent, an adult child or a sibling.

The order temporarily bars green card holders from sponsoring a spouse or child for permanent residency.

It also stops individuals from receiving green cards to enter the U.S. through other means, such as employment or the EB-1 "extraordinary ability" category.

Who is exempt?

There are several important carve-outs.

Spouses and children under 21 of American citizens can still get green cards.

Medical professionals, defined as "a physician, nurse, or other healthcare professional" working to combat COVID-19, are exempt, and may bring their spouses and unmarried kids under 21.

People applying for a green card though the EB-5 program, which requires an investment of at least $900,000 that is expected to create jobs, are exempt from the ban.

Members of the U.S. military are also excluded from the prohibition.

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The order similarly exempts people "whose entry would be in the national interest," as determined by officials like the Secretary of State or Secretary of Homeland Security.

What about temporary work visas?

The order does not prevent people from getting non-immigrant visas that are granted on a temporary basis and do not confer permanent residency or the promise of citizenship.

That includes H-1B specialty workers, H-2A agriculture workers and others.

The executive order doesn't void any existing visa.

Will this order affect tourists?

No.

Does this affect people already in the U.S.?

The order doesn't stop appear to stop foreigners lawfully here on visas from applying for green cards through the regular channels, said Greg Siskind, an immigration lawyer based in Memphis, Tennessee.

"If they're here on a non-immigrant visa, they can adjust status in the U.S. and don't have to make an entry," he said.

Does this stop green card holders from becoming citizens?

No. They're still eligible to apply for naturalization through the existing channels.

Wait. Isn't immigration already on hold?

Effectively, yes. Citizenship and Immigration Services field offices in the country are closed, which means appointments and naturalization ceremonies aren't taking place. Around the world, routine visa processing for tourists and workers has been suspended. Restrictions are in place for nonessential travel. Refugee admissions have been halted, and a new border crackdown includes turning migrants away.

To some extent, the order formalizes limits already in place.

Is it about politics?

Trump has repeatedly leaned into the issue of immigration to fire up his base. Building a wall and barring entry for Muslims were central 2016 planks. It is a powerful issue for the older, white and evangelical voters at the heart of his coalition. On Tuesday, Trump's re-election campaign sent an email to supporters promoting the tweet and saying their "input is crucial to the President's next steps."

But overall, the U.S. isn't sold on Trump's vision. Polls show that Americans oppose the wall and are split on the restrictions on travel from majority-Muslim nations. A recent YouGov survey found the U.S. evenly divided, with 46 percent approving of the president's handling of immigration and 46 percent disapproving.

What are Democrats saying?

Democrats have criticized the move, accusing Trump of seeking to distract from his failures in dealing with the coronavirus by scapegoating immigrants. "Xenophobe. In. Chief," tweeted House Democratic Caucus Chairman Hakeem Jeffries of New York. And Rep. Joaquin Castro, D-Texas, chairman of the Congressional Hispanic Caucus, called it "an authoritarian-like move to take advantage of a crisis and advance his anti-immigrant agenda."

How long will this last?

The order takes effect at 11:59 p.m. eastern daylight time on April 23, 2020 and terminates after 60 days. By 50 days of its signing, the Secretary of Homeland Security is tasked with recommending to Trump whether he should continue or alter it.

"Existing immigrant visa processing protections are inadequate for recovery from the COVID-19 outbreak," Trump wrote in the order, declaring the new immigrants he’s prohibiting to be "detrimental to the interests of the United States."

Where does Trump get the authority to do this?

The main statute cited in the order is Section 212(f) of the 1952 Immigration and Nationality Act, which gives the president broad authority to block the "entry" of categories of people he deems "detrimental" to U.S. interests.

It was previously invoked to ban narrow categories of individuals, including human rights violators and refugees from Cuba and Haiti. President Trump has sought to expand its use.

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Did Trump cite this law for the Muslim ban?

Yes.

And there are other similarities. Trump's travel ban began as a sweeping call for a "total and complete shutdown of Muslims entering the United States," but eventually it narrowed to apply to several majority-Muslim nations, with national security as the justification, so it could withstand legal scrutiny.

The new order is narrower than Trump suggested Monday in a tweet, which said he'd be "signing an Executive Order to temporarily suspend immigration into the United States. Like the Muslim ban, his new order could also face lawsuits.