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Confrontations over immigration and border security are moving to the center of the struggle between the two parties, both in Washington, D.C., and beyond. And yet the most explosive immigration clash of all may still lie ahead.

In just the past few days, Washington has seen the collapse of a bipartisan Senate deal to toughen border security amid opposition from former President Donald Trump and the House Republican leadership, as well as a failed vote by House Republicans to impeach Department of Homeland Security Secretary Alejandro Mayorkas for allegedly refusing to enforce the nations immigration laws. Simultaneously, Texas Republican Governor Greg Abbott, supported by more than a dozen other GOP governors, has renewed his attempts to seize greater control over immigration enforcement from the federal government.

Cumulatively these clashes demonstrate how much the terms of debate over immigration have moved to the right during President Joe Bidens time in office. But even amid that overall shift, Trump is publicly discussing immigration plans for a second presidential term that could quickly become much more politically divisive than even anything separating the parties now.

Trump has repeatedly promised that, if reelected, he will pursue the Largest Domestic Deportation Operation in History, as he put it last month on social media. Inherently, such an effort would be politically explosive. Thats because any mass-deportation program would naturally focus on the largely minority areas of big Democratic-leaning cities where many undocumented immigrants have settled, such as Los Angeles, Houston, Chicago, New York, and Phoenix.

What this means is that the communities that are heavily Hispanic or Black, those marginalized communities are going to be living in absolute fear of a knock on the door, whether or not they are themselves undocumented, David Leopold, a former president of the American Immigration Lawyers Association, told me. What hes describing is a terrifying police state, the pretext of which is immigration.

How Trump and his advisers intend to staff such a program would make a prospective Trump deportation campaign even more volatile. Stephen Miller, Trumps top immigration adviser, has publicly declared that they would pursue such an enormous effort partly by creating a private red-state army under the presidents command. Miller says a reelected Trump intends to requisition National Guard troops from sympathetic Republican-controlled states and then deploy them into Democratic-run states whose governors refuse to cooperate with their deportation drive.

Such deployment of red-state forces into blue states, over the objections of their mayors and governors, would likely spark intense public protest and possibly even conflict with law-enforcement agencies under local control. And that conflict itself could become the justification for further insertion of federal forces into blue jurisdictions, notes Joseph Nunn, a counsel in the Liberty & National Security Program at the Brennan Center for Justice at NYU Law School.

From his very first days as a national candidate in 2015, Trump has intermittently promised to pursue a massive deportation program against undocumented immigrants. As president, Trump moved in unprecedented ways to reduce the number of new arrivals in the country by restricting both legal and illegal immigration. But he never launched the huge deportation force or widespread removals that, he frequently promised, would uproot the estimated 11 million undocumented immigrants already in the United States during his time in office. Over Trumps four years, in fact, his administration deported only about a third as many people from the nations interior as Barack Obamas administration had over the previous four years, according to a study by the nonpartisan Migration Policy Institute.

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Exactly why Trump never launched the comprehensive deportation program he promised is unclear even to some veterans of his administration. The best answer may be a combination of political resistance within Congress and in local governments, logistical difficulties, and internal opposition from the more mainstream conservative appointees who held key positions in his administration, particularly in his first years.

This time, though, Trump has been even more persistent than in the 2016 campaign in promising a sweeping deportation effort. (Those Biden has let in should not get comfortable because they will be going home, Trump posted on his Truth Social site last month.) Simultaneously, Miller has outlined much more explicit and detailed plans than Trump ever did in 2016 about how the administration would implement such a deportation program in a second term.

Dismissing these declarations as merely campaign bluster would be a mistake, Miles Taylor, who served as DHS chief of staff under Trump, told me in an interview. If Stephen Miller says it, if Trump says it, it is very reasonable to assume thats what they will try to do in a second term, said Taylor, who later broke with Trump to write a New York Times op-ed and a book that declared him unfit for the job. (Taylor wrote the article and book anonymously, but later acknowledged that he was the author.)

Officials at DHS successfully resisted many of Millers most extreme immigration ideas during Trumps term, Taylor said. But with the experience of Trumps four years behind them, Taylor told me Trump and Miller would be in a much stronger position in 2025 to drive through militant ideas such as mass deportation and internment camps for undocumented migrants. Stephen Miller has had the time and the battle scars to inform a very systematic strategy, Taylor said.

Miller outlined the Trump teams plans for a mass-deportation effort most extensively in an interview he did this past November on a podcast hosted by the conservative activist Charlie Kirk. In the interview, Miller suggested that another Trump administration would seek to remove as many as 10 million foreign-national invaders who he claims have entered the country under Biden.

To round up those migrants, Miller said, the administration would dispatch forces to go around the country arresting illegal immigrants in large-scale raids. Then, he said, it would build large-scale staging grounds near the border, most likely in Texas, to serve as internment camps for migrants designated for deportation. From these camps, he said, the administration would schedule near-constant flights returning migrants to their home countries. So you create this efficiency by having these standing facilities where planes are moving off the runway constantly, probably military aircraft, some existing DHS assets, Miller told Kirk.

In the interview, Miller acknowledged that removing migrants at this scale would be an immense undertaking, comparable in scale and complexity to building the Panama Canal. He said the administration would use multiple means to supplement the limited existing immigration-enforcement personnel available to them, primarily at U.S. Immigration and Customs Enforcement, better known as ICE. One would be to reassign personnel from other federal law-enforcement agencies such as the Bureau of Alcohol, Tobacco, Firearms and Explosives and the DEA. Another would be to deputize local police and sheriffs. And a third would be to requisition National Guard troops to participate in the deportation plans.

Miller offered two scenarios for enlisting National Guard troops in removing migrants. One would be in states where Republican governors want to cooperate. You go to the red-state governors and you say, Give us your National Guard, he said. We will deputize them as immigration-enforcement officers.

The second scenario, Miller said, would involve sending National Guard forces from nearby Republican-controlled states into what he called an unfriendly state whose governor would not willingly join the deportation program.

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Even those sweeping plans understate the magnitude of the effort that mass deportations would require, Jason Houser, a former chief of staff at ICE under Biden, told me. Removing 500,000 to 1 million migrants a year could require as many as 100,000150,000 deputized enforcement officers, Houser believes. Staffing the internment camps and constant flights that Miller is contemplating could require 50,000 more people, Houser said. If you want to deport a million a yearand Im a Navy officeryou are talking a mobilization the size of a military deployment, Houser told me.

Enormous legal resources would be required too. Immigration lawyers point out that even if Trump detained migrants through mass roundups, the administration would still need individual deportation orders from immigration courts for each person it wants to remove from the country. Its not as simple as sending Guardsmen in to arrest everyone who is illegal or undocumented, said Leopold, the immigration lawyer.

All of this exceeds the staffing now available for immigration enforcement; ICE, Houser said, has only about 6,000 enforcement agents. To fill the gap, he said, Trump would need to transfer huge numbers of other federal law-enforcement agents, weakening the ability of agencies including the DEA, the FBI, and the U.S. Marshals Service to fulfill their principal responsibilities. And even then, Trump would still need support from the National Guard to reach the scale hes discussing.

Even if Trump used National Guard troops in supporting roles, rather than to break down doors in pursuit of migrants, they would be thrust into highly contentious situations, Houser said.

You are talking about taking National Guard members out of their jobs in Texas and moving them into, say, Philadelphia and having them do mass stagings, Houser said. Literally as Philadelphians are leaving for work, or their kids are going to school, they are going to see mass-deportation centers with children and mothers who were just in the community working and thriving. He predicts that Trump would be forced to convert warehouses or abandoned malls into temporary relocation centers for thousands of migrants.

Adam Goodman, a historian at the University of Illinois at Chicago and the author of The Deportation Machine, told me, Theres no precedent of millions of people being removed in U.S. history in a short period of time. The example Trump most often cites as a model is Operation Wetback, the mass-deportation programnamed for a slur against Mexican Americanslaunched by President Dwight Eisenhower in 1954. That program involved huge sweeps through not only workplaces, but also heavily Mexican American communities in cities such as Los Angeles. Yet even that effort, despite ensnaring an unknown number of legal residents, removed only about 250,000 people, Goodman said. To deport the larger numbers Trump is promising, he would need an operation of much greater scale and expense.

The Republican response to Texass standoff with the Biden administration offers Trump reason for optimism that red-state governors would support his ambitious immigration plans. So far, 14 Republican-controlled states have sent National Guard troops or other law-enforcement personnel to bolster Abbott in his ongoing efforts to assert more control over immigration issues. The Supreme Court last month overturned a lower-court decision that blocked federal agents from dismantling the razor-wire barriers Texas has been erecting along the border. But Abbott insists that hell build more of the barriers nonetheless. We are expanding to further areas to make sure we will expand our level of deterrence, Abbott declared last Sunday at a press conference near the border, where he was joined by 13 other GOP governors. Abbott has said he expects every red state to eventually send forces to back his efforts.

But the National Guard deployments to Texas still differ from the scenario that Miller has sketched. Abbott is welcoming the personnel that other states are sending to Texas. In that sense, this deployment is similar to the process under which George W. Bush, Obama, Trump, and now Biden utilized National Guard troops to support federal immigration-enforcement efforts in Texas and, at times, other border states: None of the governors of those states has opposed the use of those troops in their territory for that purpose.

The prospect of Trump dispatching red-state National Guard troops on deportation missions into blue states that oppose them is more akin to his actions during the racial-justice protests following the murder of George Floyd in summer 2020. At that point, Trump deployed National Guardsmen provided by 11 Republican governors to Washington, D.C., to quell the protests.

The governors provided those forces to Trump under whats known as hybrid status for the National Guard (also known as Title 32 status). Under hybrid status, National Guard troops remain under the technical command of their states governor, even though they are executing a federal mission. Using troops in hybrid status isnt particularly unusual; what made that deployment unprecedented, in Joseph Nunns phrase, is that the troops were deployed over the objection of D.C. Mayor Muriel Bowser.

The hybrid status that Trump used in D.C. is probably the model the former president and Miller are hoping to use to send red-state National Guard forces into blue states that dont want them, Nunn told me. But Nunn believes that federal courts would block any such effort. Trump could ignore the objections from the D.C. government because its not a state, but Nunn believes that if Trump sought to send troops in hybrid status from, say, Indiana to support deportation raids in Chicago, federal courts would say that violates Illinois constitutional rights. Under the Constitution, the states are sovereign and coequal, Nunn said. One state cannot reach into another state and exercise governmental power there without the receiving states consent.

But Trump could overcome that obstacle, Nunn said, through a straightforward, if more politically risky, alternative that he and his aides have already discussed. If Trump invoked the Insurrection Act, which dates back to 1792, he would have almost unlimited authority to use any military asset for his deportation program. Under the Insurrection Act, Trump could dispatch the Indiana National Guard into Illinois, take control of the Illinois National Guard for the job, or directly send in active-duty military forces, Nunn said.

There are not a lot of meaningful criteria in the Insurrection Act for assessing whether a given situation warrants using it, and there is no mechanism in the law that allows the courts or Congress to check an abuse of the act, Nunn told me. There are quite literally no safeguards.

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The Insurrection Act is the legal tool presidents invoked to federalize control over state National Guards when southern governors used the troops to block racial integration. For Trump to invoke the Insurrection Act to instead target racial minorities through his deportation program might be even more politically combustible than sending in National Guard troops through hybrid status during the 2020 D.C. protests, Nunn said. But, like many other immigration and security experts I spoke with, Nunn believes those concerns are not likely to dissuade a reelected Trump from using the Insurrection Act if courts block his other options.

In fact, as Ive written, a mass-deportation program staffed partially with red-state National Guard forces is only one of several ideas that Trump has embraced for introducing federal forces into blue jurisdictions over the objections of their local leaders. Hes also talked about sending federal personnel into blue cities to round up homeless people (and place them in camps as well) or just to fight crime. Invoking the Insurrection Act might be the necessary predicate for those initiatives as well.

These plans could produce scenes in American communities unmatched n our history. Leopold, to take one scenario raised by Miller in his interview, asks what would happen if the Republican governor of Virginia, at Trumps request, sends National Guard troops into Maryland, but the Democratic governor of that state orders his National Guard to block their entry? Similarly, in a huge deportation sweep through a residential neighborhood in Los Angeles or Chicago, its easy to imagine frightened migrant families taking refuge in a church and a Democratic mayor ordering local police to surround the building. Would federal agents and National Guard troops sent by Trump try to push past the local police by force?

For all the tumult that the many disputes over immigration are now generating, these possibilities could prove far more disruptive, incendiary, and even violent.

What we would expect to see in a second Trump presidency is governance by force, Deana El-Mallawany, a counsel and the director of impact programs at Protect Democracy, a bipartisan group focused on threats to democracy, told me. This is his retribution agenda. He is looking at ways to aggrandize and consolidate power within the presidency to do these extreme things, and going after marginalized groups first, like migrants and the homeless, is the way to expand that power, normalize it, and then wield it more broadly against everybody in our democracy.