Massachusetts Attorney General Maura Healey said Tuesday she plans to join her counterparts in other states in a lawsuit to defend the Deferred Action for Childhood Arrivals program, which President Trump is moving to rescind.

The move could affect 800,000 people across the country, and 8,000 in Massachusetts. Supporters of the program, who call them "Dreamers," say they were brought to the US as children, they've lived here for at least ten years and they have no criminal records.

US Attorney Jeff Sessions earlier on Tuesday announced plans to wind down the program, giving Congress a six-month window to come up with a replacement. Sessions called the program, created by President Obama in 2012, an unlawful "overreach."

"This is a shameful decision," Healey, D-Charlestown, said while standing next to immigration activists, Mayor Marty Walsh, D-Boston, and US Sen. Ed Markey, D-Mass.

Healey said her office plans to pursue "all legal strategies" to defend the DACA program. Her office has repeatedly filed lawsuits over against the Trump administration, ranging from environmental issues like federal emissions standards to the travel ban announced in the early days of the administration.

"At this point, my question to the president and to our US attorney general is 'whose side are you on?'" Healey said.

"What does it say about us if we turn our backs on these young people, on these young Americans? What does it say about us if we play politics with their future?" she added. "Attacking the dreamers isn't just a betrayal of our families, it's a betrayal of our most basic values, about our shared American values and the promise of the American dream."

Walsh said his office is available to offer information and support for anybody affected by the Trump administration's move.

Directing his comments to undocumented immigrants, Walsh said, "Our office is a safe place for you to call."

Gov. Charlie Baker, a Republican, did not join the press conference but also expressed opposition to rescinding the program. The Trump administration is making the "wrong decision," Baker said in a statement.