President-elect Trump during the campaign promised “the largest deportation in the history of our country.” Polls taken during the campaign found widespread public support.

In an Axios poll this spring, 51 percent of respondents supported “mass deportations of undocumented immigrants,” including 42 percent of Democrats and 45 percent of Latinos.

A CBS News poll in June found 62 percent support for a “new national program to deport all undocumented immigrants,” including a third of Democrats.

Trump’s decisive victory this week gives him the mandate to make good on his deportation promise starting in January.

And that gives illegal aliens a couple of months to get out while the getting is good.

Mitt Romney was widely mocked during his 2012 run for the White House when he said he supported “self-deportation” as the way to reduce the illegal population. This approach, which my own Center for Immigration Studies pioneered as “attrition through enforcement,” was described by Romney as “people decide they can do better by going home because they can’t find work here because they don’t have legal documentation to allow them to work here.”

There’s more to it than just that, but the point is to get illegal aliens to return home on their own by making it impractical to stay. Romney took it too far, plaintively protesting that “we’re not going to round people up,” when, in fact, some significant number of people will have to be taken into custody and forcibly removed.

But the basic idea is sound. Persuading illegal aliens to go home on their own saves the government time and money.

And it’s also preferable for the illegal aliens themselves, allowing them to return on their own terms. They can settle their affairs, pack up their belongings, and go home for Christmas — and not come back.

Nor is this a pipe dream. Even as new illegal aliens arrive, some of those already here move back home. That churn in the illegal population is why the total number fluctuated around 10 to 12 million for so long (it’s 15 million or more now, after four years of Biden-Harris-Mayorkas) — new illegal aliens were always arriving, but current ones also were leaving (while others either finagled green cards or died, thus no longer being illegal aliens).

Illegal aliens move back for any number of reasons — they earned their target sum of money to start a new business in their hometown, or an elderly parent had to be cared for, or even that little Mario came home one day from P.S. 666 insisting on being called Maria.

This is hard to estimate, but the Center for Migration Studies (a Catholic Church–sponsored think tank in New York) estimated that from 2010 to 2019, more than a quarter million Mexicans (both legal and illegal) moved back home each year. And other research by CMS suggests that the number of all immigrants (legal and illegal) who left the foreign-born population (i.e., either died or emigrated, mostly the latter, obviously) ranged from half a million to a million and a half per year during the same time period. Even more people entered, of course, but the point is there’s lots of churn. The goal of an attrition or self-deportation strategy is to harness the churn, as it were, and get more people to leave than come in.

More evidence that people go home: The CIA estimates that the country with the world’s third-highest rate of net immigration is . . . Venezuela, one of the major sources of illegal immigration to the United States under Biden, with nearly 900,000 “encounters” over the past four years. The No. 1 recipient of immigration as a share of its population? Ukraine. In neither case is this driven by foreigners going there to “seek a better life,” but rather people returning to their homelands.

Trump often points to the large-scale deportations under Eisenhower as a model for his own initiatives. The awkwardly (but officially) named “Operation Wetback” did, in fact, round up illegal aliens and deport them, but half or more of the illegal aliens who returned to Mexico during the operation did so on their own, wanting to avoid arrest.

My colleague Andrew Arthur, in the December issue of National Review magazine, highlights a more recent example of self-deportation at work. After 9/11, the National Security Entry-Exit Registration System (NSEERS) was established for nationals of certain Muslim-majority countries. It resulted in the deportation of some 1,500 Pakistani illegal aliens, and self-deportation of ten times as many.

Many immigrants (legal or illegal), especially from Latin America, visit the old folks at home for Christmas. To harness this for the purposes of self-deportation, the Trump transition will want to announce some specific measures now, before the president takes office — and make sure those plans are amplified in immigrant-oriented media.

For example, illegal aliens from El Salvador who were in the U.S. at the time of a series of earthquakes in their homeland were given “Temporary” Protected Status, including work permits, “because El Salvador temporarily was unable to handle adequately the return of its nationals.” I use scare quotes in the name of the program because this was in 2001.

This short-term status kept being renewed for more than 200,000 illegal aliens, without anyone giving it much thought, until the first Trump administration tried to let it lapse, but was obstructed by activist judges. The next renewal is set for March 9, 2025, and the Trump transition should advertise now that it will aggressively reengage the legal fight, which it is sure to win if it sticks to it, so that people should start packing. After all, El Salvador now has a lower homicide rate than the United States and even the Biden DHS deports thousands of people there each year, so the excuse that Salvadoran illegals can’t be expected to go home is absurd on its face.

Another opportunity: The Biden DHS runs two programs allowing some 70,000 inadmissible aliens each month to schedule their illegal immigration using the CBP One cell phone app. They are let into the country using “parole,” a narrow, limited power that this administration has flagrantly abused, letting in more than 1 million people who have no right to be here, just via these two programs. Trump will certainly stop this scheme on Day One, but he should also announce now that all grants of parole (and the work permits that accompany it) for people already in the U.S. will be revoked rather than allowed to run the two-year course Biden’s DHS has authorized. The ACLU or one of its many comrades will want to sue, but as the USCIS page makes clear: “We may revoke parole at any time and without notice if we determine that parole is no longer warranted.”

All of this is designed to get the deportation ball rolling before Inauguration Day. It might well be that most illegal aliens will decide to stick around and take their chances. Others will be persuaded by anti-borders crusaders that they can prevail in court. But experience shows that some significant number of illegal aliens can indeed be persuaded to self-deport. It would be easier for everyone involved, and more dignified for the departing immigrants than the alternative.