The filing assures renewed attention to President Donald Trump's position that the ACA should be eliminated, including its subsidies and popular rules banning insurers from charging more to people with pre-existing conditions.

The Trump administration is hardening its legal position toward Obamacare, arguing now the entire law is unconstitutional in a shift that promises to bring the issue to the forefront of the 2020 election campaign.

The position is a change for the Justice Department after it argued last year that large parts of the 2010 law — but not all of it — should be struck in the case Texas v. U.S., which is pending before the Fifth Circuit Court of Appeals. A trial court judge sided with Texas and voided the law in a December ruling. The Justice Department now says that the entire law, enacted under President Barack Obama, should be thrown out.

Related: The dismantling of the ACA: An (updated) timeline

The filing assures renewed attention to President Donald Trump's position that the Affordable Care Act, known as Obamacare, should be eliminated, including its subsidies and popular rules banning insurers from charging more to people with pre-existing conditions.

Trump's move, which could prove to be a gift for Democrats, prompted a swift response from House Speaker Nancy Pelosi. “Tonight in federal court, the Trump administration decided not only to try to destroy protections for Americans living with pre-existing conditions, but to declare all-out war on the health care of the American people,” she said in a statement.

Senate Minority Leader Chuck Schumer, a New York Democrat, also weighed in, claiming on Twitter that the Trump administration was focusing on “taking away your health care.”

The debate over the ACA, which Republicans tried unsuccessfully to repeal in 2017, caused heartburn for the party in the 2018 midterm elections and was a focal point for Democrats on the campaign trail.

Democratic strategist and campaign veteran Jesse Ferguson said Trump's party “lost the midterms” as a result of its position on health care, but “he seems determined to put his hand on that hot stove again and again.”

Exit polls published by CNN found that health care was the top issue for 2018 voters in House elections across the country. The 41 percent who cited it preferred Democratic candidates over Republicans by a jarring margin of 75 to 23 percent.

Yet it's an issue Democrats have struggled to stay focused on after taking the House in January and effectively neutering the Republican threat to repeal the 2010 law. The GOP had tried to undermine and undo the Affordable Care Act almost from the moment Obama signed it. Trump's vow to repeal the law was a central promise of his 2016 campaign.

“If the Trump Administration gets its way, millions of people will be stripped of their health insurance. It would devastate Americans across the country,” Representative Joaquin Castro, a Texas Democrat, said late Monday night.

Tom Perez, chairman of the Democratic National Committee, said in a statement issued Tuesday that the filing fits with the decade-long goal of overturning the law by Republicans and now Trump. “This filing moves them one step closer to throwing the financial security and peace of mind of millions — not to mention one of the largest sectors of our economy –into a tailspin,” he said.

Texas and other states that brought the lawsuit assert that because Congress in 2017 zeroed out the tax penalty for violating Obamacare's individual mandate to buy insurance, the provision is no longer constitutional, and that the rest of the law is “inseverable” from it and “therefore invalid.”

In the filing with the Fifth Circuit dated Monday, the Justice Department wrote that it had “determined that the district court's judgment should be affirmed. Because the United States is not urging that any portion of the district court's judgment be reversed, the government intends to file a brief on the appellees' schedule.”

The Justice Department filing came just as Trump was taking a victory lap after Special Counsel Robert Mueller's probe didn't find evidence that the president's campaign conspired with Russians to manipulate the 2016 election, according to a summary of the report by Attorney General William Barr.

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