President Donald Trump announced on the eve of launching his re-election campaign that Immigration and Customs Enforcement would soon deport "millions" of undocumented immigrants living in the United States.

"Next week ICE will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States," Trump tweeted Monday night, less than 24 hours before officially opening his re-election bid with a rally in Orlando, Florida.

Two Department of Homeland Security officials told NBC News that the “millions” figure the president used in his tweet was likely overblown.

The agency's acting director, Mark Morgan, recently told reporters that he planned to ramp up interior immigration enforcement and deport more undocumented families. In a statement, ICE said the agency "will continue to conduct interior enforcement without exemption for those who are in violation of federal immigration law."

"This includes routine targeted enforcement operations, criminals, individuals subject to removal orders, and work site enforcement," the agency added. "This is about addressing the border crisis by upholding the rule of law and maintaining the integrity of the immigration system, as created by Congress.”

An administration official said deportation orders were issued for more than 1 million undocumented immigrants "at great time and expense, and yet illegal aliens not only refuse to appear in court, they often obtain fraudulent identities, collect federal welfare, and illegally work in the United States."

"Enforcing these final judicial orders is a top priority for Immigration and Customs Enforcement — willful defiance of our laws, and the defrauding of the American people with fraudulent asylum claims, will not be tolerated,” the official added. The statement did not specify what actions, if any, the president plans to take next week.

Deportations from the interior of the U.S. are down because of a lack of bed space at detention centers due to the influx of migrants being apprehended and held in ICE custody after crossing the border.

After being arrested, migrants are held in detention centers while repatriation arrangements are made with their home countries, but those centers are at or near capacity because of the influx of immigrants.

Deportations peaked at around 400,000 a year at the beginning of this decade and decreased to about 250,000 or fewer undocumented immigrants annually in recent years, according to ICE statistics.

This isn't the first time Trump has pledged to rapidly deport millions of undocumented immigrants. During a post-election interview with CBS News' "60 Minutes" in November 2016, Trump said he planned to immediately deport 2 million to 3 million undocumented immigrants with "criminal records" shortly after his inauguration. In an August 2016 immigration speech, Trump said that those deportations would begin on "day one," saying, "My first hour in office, those people are gone."

In a 2015 interview with MSNBC's "Morning Joe," Trump said he would create a "deportation force" to remove the millions of undocumented immigrants living in the U.S.

House Speaker Nancy Pelosi, D-Calif., responded to Trump's latest deportation pledge Tuesday afternoon, calling on him to "walk away from these cruel, ineffective and discriminatory policies, and work with Democrats to support smart, effective immigration reform that honors our values and keeps families together and safe."

"The President’s new threat of a mass deportation dragnet is an act of utter malice and bigotry, designed solely to inject fear in our communities," she said. "This plan revives the horror of the President’s family separation policy, inflicting its inhumanity on countless hardworking families across America."