The Trump administration may tighten criteria, declare a state of emergency, and mobilize the military to carry out what would be the largest deportation of undocumented immigrants in U.S. history.

During his campaign, Donald Trump repeatedly criticized undocumented immigrants, claiming they "taint" the American bloodline and bring "bad genes" into the country. He pledged to undertake the largest deportation operation in U.S. history if he returns to the White House.

This warning is becoming a reality. Following his victory, Trump appointed former Immigration and Customs Enforcement (ICE) director Tom Homan, known for his hardline stance on immigration, as the "border czar" tasked with overseeing a large-scale deportation effort. Trump's advisory team is reportedly drafting executive orders to enable him to launch deportation operations on his first day in office.

According to the Department of Homeland Security (DHS), there are approximately 11 million undocumented immigrants living in the U.S., and Trump's campaign could target a significant portion of this population. Experts believe that to handle such a large number, Trump may begin by focusing on recently arrived border-crossers. This would involve expanding deportation criteria, revoking protective orders for immigrants, and invoking the Alien Enemies Act of 1798. Andrew Selee, president of the Migration Policy Institute in Washington, D.C., suggests that Trump could initiate his campaign by targeting hundreds of thousands of immigrants who entered the U.S. through the CBP One program established by President Joe Biden.

CBP One is a free app that allows migrants in Mexico to schedule appointments with U.S. Customs and Border Protection (CBP) at one of eight border crossings to receive humanitarian permits. These permits allow them to legally enter the U.S. and work for two years while awaiting asylum hearings under U.S. immigration law.

U.S. officials emphasize that CBP One is merely an appointment scheduling tool and not a formal asylum application. Nevertheless, migrants have used it as a pathway to enter the U.S. legally.

Data from U.S. border officials shows that, as of August, around 800,000 immigrants, primarily from Haiti, Mexico, and Venezuela, entered the U.S. using CBP One.

"Trump is almost certain to quickly revoke the two-year reprieve policy for those entering the U.S. with CBP One," Selee told NPR.

The Trump administration may also reactivate the Migrant Protection Protocols, or "Remain in Mexico" policy, requiring migrants to stay outside the U.S. while awaiting asylum hearings. CBP One is under DHS control. Trump has nominated South Dakota Governor Kristi Noem, a longtime supporter, as DHS Secretary for his second term.

Another possible target for Trump is immigrants with Temporary Protected Status (TPS), a policy allowing people fleeing extreme conditions in their home countries to seek refuge in the U.S., as well as those entering under programs for nationals from Cuba, Venezuela, Haiti, and Nicaragua.

CBP reports that from January 2023 to August of this year, approximately 500,000 immigrants entered the U.S. through humanitarian flights under TPS provisions.

"These policies will be terminated very quickly, almost immediately," said Dan Stein, a member of the nonprofit Federation for American Immigration Reform (FAIR), based in Washington, D.C. FAIR is connected to Trump's team and served as a staffing source during his first term.

DHS currently offers TPS protection to individuals from 16 countries, including El Salvador, Ukraine, Syria, Somalia, and Haiti. During his first term, the Trump administration sought to end TPS for over 300,000 people. Many challenged this move in court, citing racial animosity from the Trump administration, and received protective rulings through the end of his presidency. During the Biden administration, DHS Secretary Alejandro Mayorkas issued a memorandum outlining deportation priorities, focusing on national security and public safety threats and directing ICE to "consider all relevant facts and circumstances" regarding deportation cases instead of automatically prioritizing criminal convictions.

Trump's team may revoke Mayorkas' memorandum on day one of his second term, possibly as part of a package of executive orders aimed at removing "bureaucratic red tape" obstructing deportation processes.

Selee predicts that Trump may alter regulations to make it easier for ICE to detain and deport undocumented immigrants.

Trump has floated expanding detention facilities for undocumented immigrants, potentially using military bases within the U.S.

According to Selee, employing military bases or deploying troops would require invoking the Alien Enemies Act of 1798, which Trump referenced during his campaign. On November 18, Trump reiterated that he "will declare a national emergency and use the military" for mass deportations when he reshared a post about the plan on social media.

Trump could also exert pressure through measures like threatening visa restrictions or sanctions to compel countries to accept deportees, particularly those with criminal records.

Both the Trump and Obama administrations have used such leverage, while the Biden administration has not. In the first 100 days of his second term, Trump's immigration team could evaluate which countries pose the "greatest obstacles" and consider sanctions threats.

This strategy would require cooperation from the State Department, and Trump is expected to appoint like-minded individuals to key positions, including Secretary of State. Trump has nominated Florida Senator Marco Rubio, a loyal ally, for this role.

However, Trump's ambition for mass deportations faces significant hurdles.

Trump's advisers say they will prioritize deporting people with criminal records and those with final deportation orders from immigration courts. Still, this represents a massive group, estimated at 1.2 million individuals by the American Immigration Council in 2022.

To date, fiscal year 2013 marked a record high for deportations in the U.S., with over 430,000 people removed—far below Trump's projected numbers. Locating, detaining, and deporting such a vast number of people would require extensive resources, said John Sandweg, acting ICE director in 2013-2014. Congressional approval for funding would be necessary, and even with a budget, Trump's administration would need to recruit, vet, and train numerous additional ICE officers.

ICE currently employs 7,000 officers, conducting 250,000 deportations annually, according to ICE figures. If Trump aims to quadruple this capacity, ICE training academies would be overwhelmed.

NPR asked Trump's transition team whether the President-elect has a detailed plan for implementing mass deportations.

"The American people have overwhelmingly elected Trump back to the White House, entrusting him with the mandate to fulfill his campaign promises. He will carry them out," said Karoline Leavitt, spokesperson for Trump's transition team. Meanwhile, anxiety has gripped undocumented immigrant communities across the U.S. following Trump's election victory.

However, some undocumented immigrants, like Gabriela, believe Trump's policies will not affect them. Gabriela, born in Bolivia, has lived in the U.S. illegally for two decades and works as a housekeeper in Maryland.

"Honestly, I'm not afraid," Gabriela said. "Criminals and people with records should worry. I work and pay taxes. Plus, I'm undocumented, so how would they even know about me?"