ICE will not comment on operational details of the raids, spokesman Matthew Bourke said, but the department is focusing primarily on those it considers dangerous.
“ICE prioritizes the arrest and removal of unlawfully present aliens who pose a threat to national security, public safety and border security,” Bourke said.
Mark Morgan, acting commissioner for US Customs and Border Protection who was acting ICE director at the time, said the raids were postponed because operations details had been leaked. Former acting ICE director John Sandweg also expressed concern.
“You never want the target to know you’re coming. You want that element of surprise because it keeps you safe,” he said. “From an effective perspective, that’s why you don’t announce these things.”
Trump has repeatedly tweeted about the impending operation, which is expected to target recent arrivals to the country.
In February, ICE sent around 2,000 letters to families who already had received final orders of removal by judges in absentia, asking them to self-report to ICE offices by March. The upcoming operation is expected to target approximately 2,000 people, the senior immigration official said.
According to Immigration and Customs Enforcement statistics, 256,085 people were deported in fiscal year 2018, up from 226,119 removals in fiscal year 2017.
“Of course, that isn’t what ICE will go after in this, but that’s the pool of people who have been all the way through the due process chain,” he said.
Correction: A previous version of this story misstated the nature of the raids. Immigration authorities are expected to begin conducting raids targeting undocumented immigrants.
CNN’s Priscilla Alvarez reported from Washington. Eliott McLaughlin wrote from Atlanta. Devan Cole and Kevin Liptak contributed to this report.