Trump threatens to deport millions living in U.S. illegally beginning next week

"They will be removed as fast as they come in," Trump tweeted Monday night. "Mexico, using their strong immigration laws, is doing a very good job of stopping people long before they get to our Southern Border. The only ones who won't do anything are the Democrats in Congress. They must vote to get rid of the loopholes, and fix asylum! If so, Border Crisis will end quickly!"

>> See the tweets here

The Associated Press, citing an unnamed administration official, reported that the measure "would focus on the more than 1 million people who have been issued final deportation orders by federal judges but remain at large in the country."

>> Read the latest from our Washington Insider, Jamie Dupree

"These judicial removal orders were secured 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," the official said in a statement to ABC News. "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."

U.S. Immigration and Customs Enforcement generally does not announce raids ahead of time, the AP reported.

Although Acting ICE Director Mark Morgan told reporters earlier this month that the agency "will be going after individuals who have received final deportation orders," officials recently told the Washington Post that the effort wasn't imminent.

On Tuesday, Trump is scheduled to appear at a rally in Orlando, Florida, where he will formally announce that he is running for president again in 2020, the AP reported.

Read more here.

– The Associated Press contributed to this report.