President Donald Trump called Monday on Congress to come up with legislation to replace the Obama administration's Deferred Action for Childhood Arrivals (DACA) program, which postponed the deportation of some 800,000 people brought illegally into the United States when they were children.

"Congress, get ready to do your job - DACA!" Trump said in a Twitter post.

The president is expected to announce his decision on DACA, which was implemented via executive order by former President Barack Obama in 2012, on Tuesday.

Trump's tweet seems to confirm reports that he will announce the end of DACA but will give Congress six months to come up with a legilslative replacement.

Last week, conservative television network Fox News reported that DACA would be terminated, and Politico broke the story Sunday that there would be a six-month delay, giving Congress time to replace the executive order with legislation.

An announcement is expected around 11:00 am, when Attorney General Jeff Sessions, a prominent hardliner on illegal immigration in the Trump administration, will hold a press conference.

As a senator from Alabama, Sessions was a vocal opponent of DACA, arguing that it was unconstitutional.

Implemented in 2012 by Obama, DACA gave young people who were brought illegally into the US as children the opportunity to pursue education or jobs without fear of deportation.

DACA status must be renewed every two years.

The Obama administration conceived of DACA as a way to aid the intended beneficiaries of the DREAM Act, a bipartisan piece of legislation that has been stalled in Congress for more than a decade.

Some 75 percent of the so-called "dreamers" were born in Mexico, according to Citizenship and Immigration Services (USCIS).

During the 2016 presidential campaign, Trump vowed to end DACA on his first day in the White House, but he later acknowledged that the issue was "one of the most difficult" to address and promised he would deal with it "with heart."

The attorneys general of at least nine conservative states, led by Texas, challenged Obama's executive order as unconstitutional and pressured Trump to terminate the program, threatening to sue the federal government immediately if DACA is not ended.