President Trump said U.S. immigration agents are planning to make mass arrests and deportations days after striking a deal with Mexico to curb the flow of undocumented migrants. The Washington Post’s Nick Miroff explains what’s at stake. (REF:Luis Velarde/The Washington Post)

President Trump has begun his reelection bid by reviving a campaign promise to deport “millions of illegal aliens” from the United States, saying his administration will get to work on that goal “next week” with raids across the country.

But the president’s ambitious deportation goals have crashed, again and again, into the earthly reality of the U.S. immigration enforcement system.

U.S. Immigration and Customs Enforcement is averaging approximately 7,000 deportations per month from the U.S. interior, according to the agency’s latest data. With unauthorized border crossings soaring under Trump to their highest levels in more than a decade, ICE has been facing a shortage of funds and detention beds, and experts say that a large-scale push to arrest and deport hundreds of thousands of migrants would be exorbitantly expensive and highly unlikely.

For ICE, making “at large” arrests in homes and neighborhoods — the key to chipping away at the “millions” Trump wants to expel — will require significant amounts of planning, coordination and secrecy. By telegraphing plans to begin a nationwide roundup, the president has risked undermining the effectiveness of ICE’s largest and most complex enforcement operation in years.

Trump and Mark Morgan, the acting director of ICE, talked several times over recent weeks about the operation, including as recently as this weekend. But senior White House and immigration officials did not know the president planned to announce it on Twitter, a senior White House official said Tuesday, and many felt it was detracting from the launch of the campaign. But Trump is eager to appear that he is making progress on immigration and remains fixated on the issue, advisers say.

The sensitive plan is aimed at sweeping up and deporting thousands of migrant family members in major U.S. cities who were ordered to leave the country after their cases were evaluated by immigration judges. Department of Homeland Security officials say the arrests are at the heart of their attempts to deter Central American families from making the journey north.

On Tuesday, current and former ICE officials acknowledged that Trump’s unexpected tweet had blown the cover off the plan, and they predicted that would-be deportees could scatter from known addresses in the coming days, diminishing the agency’s chances for success. Lawmakers and immigrant advocates expressed alarm and outrage at the possibility that ICE would go forward with the plan, which risks separating parents and children as agents fan out to knock on doors and make mass arrests.

ICE declined to say whether Trump’s tweets referred to a specific operation in the works, but U.S. officials acknowledged privately that they are preparing to move forward with their long-planned blitz to take thousands of families into custody.

Morgan said Tuesday on “PBS NewsHour” that he hoped immigrants facing deportation would “work with us” and “come and turn themselves in to ICE agents and we will work with them to remove them to their countries.”

“We don’t want to have to go and track them down into the neighborhoods in the cities,” Morgan said. “We don’t want that and I don’t want that for the families.”

Morgan said he did not think Trump’s tweet publicizing the planned arrests put immigration agents at risk, because the president did not provide specifics. “I’m not concerned,” he said. “They’re professionals. They know exactly what they need to do.”

With hundreds of ICE agents deployed to the border in recent months, interior arrests have dipped. From October to December, the most recent period for which statistics are available, ICE deported 22,169 people from the U.S. interior, down 7 percent from the same period in 2017. About 10.5 million unauthorized immigrants are in the United States, according to the Pew Research Center.

To meet the president’s goal of “millions” of deportations, ICE would need significantly more agents and funding. ICE’s division of enforcement and removal operations has fewer than 6,000 officers nationwide who are potentially available to carry out the kind of arrests described by the president, which would entail higher risks because they would involve knocking on doors and arresting parents and children in homes and apartments.

There is division among Trump officials about whether the roundup will make for good politics and policy. But Morgan, senior Trump adviser Stephen Miller and the president support the actions, a senior White House official said, speaking on the condition of anonymity to describe the internal fissures.

Trump has repeatedly wondered why people cannot just be taken out of the country, the official said.

John Sandweg, acting ICE director in 2013 and 2014 during the Obama administration, questioned ICE’s capability to undertake such a massive operation, given the agency’s staffing and budget constraints. ICE is detaining the largest number of migrants in its history — more than 50,000 a day — and is under “incredible strain” because of an influx of Central American migrants at the U.S.-Mexico border, Sandweg said.

At its peak, ICE deported more than 400,000 immigrants during the entire 2012 fiscal year, and more than half of those were border-crossers who could be quickly sent home.

“The idea that somehow by just presidential will the agency’s going to go [up] 250 percent to the biggest, largest number of removals in its history is just ridiculous,” Sandweg said.

Arrests in neighborhoods and residential areas are complex and typically take months to plan, he said. Usually at least four officers are assigned to each arrest target, to ensure the safety of migrants, agents and bystanders.

Sandweg also noted that children require special care, and ICE has only about 3,000 beds available for family detention.

The Justice Department, which runs the immigration courts, said it is aware of at least 12,780 removal orders issued to “family units” from Sept. 24 through Friday. Of those, nearly 11,000 orders were issued in absentia, meaning the immigrant did not appear in court. The orders were mailed to their houses, said Justice Department spokesman Alexei Woltornist, with the largest numbers in Houston, Miami and Atlanta.

The plan for raids has led to upheaval at the DHS in recent months. Ronald Vitiello was removed as ICE chief in April when he raised concerns about the readiness of the plan for raids. White House frustration with the reluctance to perform the operation also contributed to the ouster of Secretary Kirstjen Nielsen.

In an interview Tuesday, Vitiello said the success of the operation should not be measured based upon how many of those on ICE’s target list are picked up. In most cases, ICE has little more than addresses for the individuals who were mailed deportation orders, and the chances that they remain at those locations are not high.

“They don’t have to get all their targets. They just have to improve compliance and increase the removal numbers of a population with a very low chance of being removed,” Vitiello said. “Without an operation like this, these families would be allowed to remain in the shadows for as long as they want to be.”

Trump told a cheering crowd in Phoenix three months before his election that he would deport millions of immigrants who had allegedly committed crimes.

“Day one, my first hour in office, those people are gone,” Trump said. “They’re going to be gone. It will be over. They’re going out. They’re going out fast.”

Tom Homan, the acting ICE director during the first 18 months of the Trump presidency, praised the president’s deportation agenda in an interview Tuesday, and he said that ICE operations targeting families during the Obama administration were a crucial migration deterrent.

Homan, who was unexpectedly named “border czar” by Trump last week but who has not yet accepted the job, said he has heard the ICE operation targeting families has been “held up” for months because senior DHS officials are anxious about the potential for public backlash.

“Part of the problem was they didn’t want the bad press,” Homan said. “But you know what? If bad media is going to stop you from doing your job, then you need to find another job.”

Houston Police Chief Art Acevedo, who serves on the DHS Homeland Security Advisory Council, suggested that the disruption also could undermine public safety. “Intentional societal disruption, creating mass fear, confusion, & panic is not good public policy or consistent with American Judeo-Christian values,” Acevedo tweeted Tuesday. “This rhetoric will push many further into the shadows, & places an already marginalized segment of society at risk.”

Rep. Bennie Thompson (D-Miss.), chair of the House Homeland Security Committee, criticized Trump’s plans and called on the president to work with Congress “toward agreeable solutions.” House Democrats have agreed that a humanitarian crisis is unfolding on the U.S.-Mexico border, but they favor better holding conditions for migrants, particularly children, who accounted for 40 percent of apprehensions in May.

ICE in June was already surpassing its fiscal 2019 budget projections for beds, with the population of adult detainees exceeding the anticipated head count by about 5,000 people, an ICE official said.

Rep. Lucille Roybal-Allard (D-Calif.), chair of the House Appropriations homeland-security subcommittee, which oversees budget issues, said Trump should “stop terrorizing immigrant families” and work with Democrats to address the issues facing the immigration system.

“Donald Trump’s new tweet continues to push cruel and hateful immigration policies that separate families and traumatize children, while doing nothing to fix our broken immigration system,” she said in a statement. “Of course, he’s not doing this to fix our immigration system: he’s doing it to throw anti-immigrant red meat to his base, and stoke their fear and fury against America’s immigrant population.”