The incoming Trump administration is already preparing to dramatically increase its capacity to detain illegal immigrants as part of the massive deportation operation it has pledged to launch in January, Fox News Digital has confirmed -- the latest sign that it plans to deliver on that promise.

President-elect Trump said during the campaign that he intends to launch a historic mass-deportation campaign in the wake of the historic migrant crisis at the southern border. It is a promise that he and top officials have repeated since his election victory last week.

Karoline Leavitt, a spokeswoman for the transition team told Fox News Digital: "The American people re-elected President Trump by a resounding margin, giving him a mandate to implement the promises he made on the campaign trail. He will deliver." 

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NBC News reported this week that the Trump administration is considering locations where it can expand immigration detention centers and that the transition team is looking at how many migrants can be held in regions across the country and talking to private prison companies about expansion.

A source familiar with the plans confirmed the report. NBC reported that the plan is to double the number of Immigration and Customs Enforcement (ICE) beds allocated by Congress, but the source said that the intention is to significantly increase the number of beds, and that a doubling of capacity was too specific.

Locations are expected to be expanded near areas where there have been significant numbers of illegal immigrants. "Sanctuary" cities like New York City, Washington D.C., and Chicago have been overwhelmed by a surge of migrants into their jurisdictions, some of whom have been bused in by Texas, so detention centers could be set up, expanded or re-opened in those areas.

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There are currently a number of ICE facilities that are not at full capacity, or that could have capacity expanded. Some cases are unique, like a facility in Adelanto, Calif., that has been largely shuttered due to a COVID-era court order.

Republicans have repeatedly hammered the Biden administration for a lower level of deportations, even amid a historic surge of migrants into the U.S. interior. Critics of the Trump plan have claimed that the cost would be too high, but immigration hawks have said that it is cheaper than allowing them to stay.

The administration may face significant pushback from Democratic governors. Mass Gov. Maura Healey said last week that "every tool in the tool box has got to be used to protect our citizens, to protect our residents and protect our states and to hold the line on democracy and the rule of law as a basic principle."

"No. Absolutely not," she said when asked whether  state police would help with deportations.

CLICK HERE FOR MORE COVERAGE OF THE BORDER SECURITY CRISIS

Trump announced three major immigration-related staffing moves this week. On Monday, he announced that former acting ICE Director Tom Homan will be the "border czar" and will be in charge of border security and overseeing the deportation operation. On Tuesday, Trump announced that Kristi Noem was his pick to lead the department of Homeland Security. 

"With Donald Trump, we will secure the border and restore safety to American communities so that families will again have the opportunity to pursue the American dream," she said in a statement.

On Wednesday, Trump announced that Stephen Miller, who spearheaded many immigration policies in Trump’s first term, will serve as assistant to the president and deputy chief of staff for policy and homeland security adviser.