WASHINGTON — President Donald Trump will phase out a program that has protected hundreds of thousands of young immigrants brought into the U.S. illegally as children and will call for Congress to find a legislative solution to protect the immigrants.

WATCH | US ATTORNEY GENERAL JEFF SESSIONS' FULL NEWS CONFERENCE ABOVE

Attorney General Jeff Sessions made the announcement Tuesday morning, calling the program "unconstitutional."

"I'm here today to announce that the program known as DACA that was effectuated under the Obama administration is being rescinded," Sessions announced.

New applications for President Barack Obama's Deferred Action for Childhood Arrivals, or DACA, program will be halted, he said.

Trump suggested in an earlier tweet Tuesday that it would be up to Congress to ultimately decide the fate of those covered by DACA, created in 2012 as a stopgap.

"Make no mistake, we are going to put the interest of AMERICAN CITIZENS FIRST!" he said on Twitter.

The administration plans to give Congress six months to come up with legislation to overhaul the program before it stops renewing permits for people covered under the program.

News of Tuesday's announcement has prompted protests, phone campaigns and rallies across the country urging him not to rescind the program.

“However well-intentioned, President Obama’s DACA program was a clear abuse of executive authority, an attempt to create law out of thin air. Just as the courts have already struck down similar Obama policy, this was never a viable long-term solution to this challenge," House Speaker Paul Ryan (R-WI), said in a statement.

Meanwhile, Rep. Lloyd Doggett (D-Texas), who represents a number of "Dreamers" in San Antonio, Austin and San Marcos, said:

“Today’s tactic represents little more than yielding to those who did not think Trump was already sufficiently anti-immigrant. This is an attempt to make Dreamers bargaining chips to achieve other Trump anti-immigrant objectives."

DACA has provided almost 800,000 young immigrants a reprieve from deportation and the ability to work legally in the country.

Former President Obama issued a statement in response to the decision, which read in part:

“ We all want safe, secure borders and a dynamic economy, and people of goodwill can have legitimate disagreements about how to fix our immigration system so that everybody plays by the rules. But that’s not what the action that the White House took today is about.  This is about young people who grew up in America – kids who study in our schools, young adults who are starting careers, patriots who pledge allegiance to our flag.  These Dreamers are Americans in their hearts, in their minds, in every single way but one: on paper… Some 800,000 young people stepped forward, met rigorous requirements, and went through background checks.  And America grew stronger as a result. But today, that shadow has been cast over some of our best and brightest young people once again… What makes us American is not a question of what we look like, or where our names come from, or the way we pray.  What makes us American is our fidelity to a set of ideals – that all of us are created equal; that all of us deserve the chance to make of our lives what we will; that all of us share an obligation to stand up, speak out, and secure our most cherished values for the next generation.  That’s how America has traveled this far.  That’s how, if we keep at it, we will ultimately reach that more perfect union.”