WASHINGTON — President-elect Donald J. Trump’s promise to deport two million to three million immigrants who have committed crimes suggested that he would dramatically step up removals of both people in the United States illegally and those with legal status. If carried out, the plan potentially would require raids by a vastly larger federal immigration force to hunt down these immigrants and send them out of the country.
Addressing the issue in an interview broadcast Sunday on the CBS program “60 Minutes,” Mr. Trump adopted a softer tone on immigrants than he did during his campaign, when he called many of them rapists and criminals. He instead referred to them as “terrific people,” saying they would be dealt with only after the border had been secured and criminals deported.
But by placing the number of people he aims to turn out of the country as high as three million, Mr. Trump raised questions about which immigrants he planned to target for deportation and how he could achieve removals at that scale.
The details are crucial to understanding the approach of a president-elect who centered his campaign on a promise to build a border wall and deport lawbreakers. On Monday, President Obama said he would urge Mr. Trump to consider leaving in place his executive actions that have shielded from deportation immigrants brought to the United States illegally as children.
A Look at the Numbers
Asked on “60 Minutes” whether he would seek to deport “millions and millions of undocumented immigrants,” Mr. Trump said his priority would be to remove “people that are criminal and have criminal records.”
“What we are going to do is get the people that are criminal and have criminal records — gang members, drug dealers, we have a lot of these people, probably two million, it could be even three million. We are getting them out of our country or we are going to incarcerate,” Mr. Trump said. “But we’re getting them out of our country, they’re here illegally.”
The Obama administration has estimated that 1.9 million “removable criminal aliens” are in the United States. That number includes people who hold green cards for legal permanent residency and those who have temporary visas. It also includes people who have been convicted of nonviolent crimes such as theft, not just those found guilty of felonies or gang-related violence.
“They certainly have that many to start,” said Jessica M. Vaughan, director of policy studies at the Center for Immigration Studies, a group that supports reduced immigration.
But even if Mr. Trump’s numbers are correct — and many immigration activists dispute them — it is not clear Mr. Trump could carry out those deportations quickly without violating due process.
In many cases, convicts would have to go through immigration courts before they could be deported. Those courts are overwhelmed with huge backlogs, so obtaining deportation orders from judges can take many months — if not many years. Thousands of immigrants are serving jail sentences that under current law cannot be curtailed. According to official figures, as of June only about 183,000 immigrants had been convicted of crimes and also had deportation orders so they could be detained and removed quickly.
Mr. Trump’s approach would in some ways be a continuation of policies Mr. Obama has pursued to focus immigration enforcement on convicted criminals.
In 2014, his administration issued guidelines instructing agents to make criminals the highest priorities for their operations. In 2015, according to Immigration and Customs Enforcement figures, the majority of the 235,413 people deported — 59 percent — were convicted criminals, while 41 percent were removed for immigration violations.
“Under the Obama administration we have already managed to calibrate our policy with heavy emphasis on criminal aliens,” said Muzaffar Chishti, the director of the New York University School of Law office of the Migration Policy Institute, a nonpartisan research group.
Since 2009, Mr. Obama has presided over the deportation of about 2.5 million immigrants, prompting sharp criticism from advocacy groups. He did so in part to build political support for a broad revision of immigration laws that would have provided a path to citizenship for immigrants in the country illegally.
Under a now-defunct program known as Secure Communities, the Obama administration used digital fingerprints shared by local law enforcement departments to find and deport immigrants who had committed crimes. Immigration and Customs Enforcement also partnered with local authorities to prioritize the arrest and detention of criminal aliens.
Both measures helped drive deportations to roughly 400,000 per year during Mr. Obama’s first term. Multiplying that number by many times would almost certainly require reinstituting a program like Secure Communities and employing vastly more immigration agents, as well as using more aggressive tactics to find and remove immigrants who may have broken the law, according to Mr. Appleby of the Center for Migration Studies of New York.
Resistance From Cities
If Mr. Trump seeks to revive programs of close cooperation between local police and federal immigration authorities, he is likely to encounter legal challenges and resistance from dozens of cities and counties that have curtailed or rejected cooperation.
Mr. Trump has said he would cut off federal funding for cities that refuse to help federal agents detain unauthorized immigrants. During his campaign, he highlighted terrible crimes by immigrants he said had escaped detection because of protective policies.
At a news conference in Chicago on Monday, Mayor Rahm Emanuel, a Democrat, sought to ease fears of deportation and harassment as he reiterated Chicago’s status as a sanctuary city for immigrants.
“It is important for families that are anxious, it is important for children and adolescents that are unsure because of Tuesday, to understand the city of Chicago is your home,” Mr. Emanuel said. “You are always welcome in this city.”
Cook County, where Chicago is, has adopted an especially restrictive policy on ties between police and federal agents. Mr. Emanuel encouraged immigrants to call a hotline for legal advice, and said Chicago would quickly set up a municipal identification program to allow undocumented immigrants access to city services.
Mayor Betsy Hodges of Minneapolis was defiant. “I will continue to stand by and fight for immigrants regardless of President-elect Trump’s threats,” she said. “If police officers were to do the work of ICE, it would harm our ability to keep people safe and solve crimes.” Mayor Ras Baraka of Newark, said the city’s protections would not change.
In California, lawmakers in a Legislature dominated by Democrats rejected Mr. Trump’s numbers and plans. “It is erroneous and profoundly irresponsible to suggest that up to three million undocumented immigrants living in America are dangerous criminals,” said Kevin de León, the president pro tempore of the Senate. He said Mr. Trump’s figures were “a thinly veiled pretense for a catastrophic policy of mass deportation,” and he told immigrants, “the State of California stands squarely behind you.”
The Los Angeles police chief, Charlie Beck, said his force would not change its policies. “We are not going to work in conjunction with Homeland Security on deportation efforts,” he said, according to The Los Angeles Times. “That is not our job, nor will I make it our job.”