As Inauguration Day nears, it’s clear that President-elect Donald Trump believes he has a mandate to enact the largest deportation in U.S. history. What happens next could forever alter what it means to be an American.

Immigration under President Joe Biden surged to levels unmatched in more than a century — an estimated net increase of 8 million migrants during his four years in office, with a majority crossing illegally, according to a Goldman Sachs report.

Biden was determined to reverse the harsh Trump 1.0 policies that limited both legal and illegal immigration. But Biden never framed this important issue for average Americans. There never was a “Biden doctrine” to help the nation understand why he believed more immigrants, refugees and asylum seekers could prove a net benefit — or sufficient federal aid to help cities and states deal with the consequences.

Finally, after Trump killed a bipartisan immigration reform bill, Biden unilaterally reimposed tighter limits on the southern border — but it was too late to save his candidacy, or that of Vice President Kamala Harris.

Now the U.S. finds itself with the highest foreign-born population in its history — over 15% — and a border better described as porous than secure. And the electorate has proven susceptible to Trump’s divisive, demonizing rhetoric.

Now that Trump is prepared to deliver on his top priority, expect the actions that follow to be swift and ugly. In particular, keep your eye on five things:

The Alien Enemies Act of 1798

There is a reason Trump and his acolytes on the campaign trail repeatedly described migrants as “invaders” and border crossings as an “invasion.” He has said he will use the Alien Enemies Act to “remove all known or suspected gang members, drug dealers or cartel members from the United States.”

The act so far has been used only in wartime, and Trump’s invocation would surely draw a legal challenge. But the Brennan Center for Justice has warned that the act’s language is so broad that “a president might be able to wield the authority in peacetime as an end run around the requirements of criminal and immigration law.”

Trump also has pledged to use the military and local law enforcement if necessary. There are prohibitions against that as well, but it’s anyone’s guess whether a conservative court will uphold them.

Workplace raids

Tom Homan, Trump’s nominee for “border czar,” and a former acting head of Immigration and Customs Enforcement (ICE), has pledged to bring back workplace raids. Once a staple of enforcement in earlier administrations, workplace raids were discontinued under Biden. The raids were disruptive to employers and sparked terror in immigrant communities, but Homan has said the message is one that needs to be sent.

He has said he will start in Chicago, a northern Mecca for immigrants that has declared itself a sanctuary city. Homan told a group in that city recently that, “If your Chicago mayor doesn’t want to help, he can step aside. But if he impedes us, if he knowingly harbors an illegal alien, I will prosecute him.” Homan has already met with the far more cooperative New York City Mayor Eric Adams, a former police officer, who later pledged his cooperation despite his city’s sanctuary laws.

Birthright citizenship

Trump has said that he intends to upend one of the most fundamental ideas about the U.S.: That no matter where in the world your parents come from, if you are born here, you are an American. It is a principle specifically enshrined in the 14th Amendment.

No president can override the Constitution with an executive order. But Trump could create havoc in the meantime by, as he has said he would, ordering the government to stop issuing Social Security numbers and passports to offspring of parents who cannot prove their legal status.

Refugee programs

Biden reduced illegal border crossings in part by expanding programs that allowed legal ones, including the policy of humanitarian parole. But the outgoing president has said he will not renew that authorization for the more than half-million immigrants who came from Venezuela, Haiti, Cuba and Nicaragua during his term.

Trump has called Biden’s version an “outrageous abuse of parole” and seeks to end it. He may also seek to end or severely restrict Temporary Protected Status, which shields more than 800,000 immigrants from specific countries against deportation.

Dreamers

The lone carrot Trump has held out to Democrats is possible action to protect Dreamers — those brought to this country illegally as children, many of whom have grown old waiting for more than temporary protection in the only homeland they’ve ever known. How genuine is that offer? That’s up to Trump, whose record is mixed. He also held out a similar promise in his first term, only to go back on it.

Hardliners in Congress have already expressed reservations about further protections for Dreamers, whose status rests on an Obama 2012 executive order called Deferred Action for Childhood Arrivals, or DACA. The order provided a temporary shield from deportation and work permits. If Trump persists, expect him to extract maximum leverage from any deal.

It should be clear even to the biggest doubters that Trump intends to follow through on what is now a decade-old pledge to crack down on immigration. But this time he has a team in place with the experience and knowledge to follow through, however brutal and a conservative Supreme Court. That could make all the difference.