The administration of US President Donald Trump has escalated its battle against Obamacare by fully siding with a court ruling that found the health care law unconstitutional.
Texas-based Judge Reed O'Connor issued his ruling in December following a lawsuit brought by conservative states, but later ordered a stay while an appeal lodged by Democratic attorneys general was being heard.
Trump's Department of Justice (DOJ) had previously taken the position that it would not defend the law's protections for people with pre-existing conditions, though other parts could stay.
But on Monday night the DOJ issued a letter saying its stance had now changed and it agreed with O'Connor's ruling in its entirety.
"The Department of Justice has determined that the district court's judgment should be affirmed," it said, adding: "The United States is not urging that any portion of the district court's judgment be reversed."