In a news conference Tuesday morning, House Judiciary Committee Chairman Rep. Jerry Nadler, D-N.Y., called the administration's move a "nakedly political decision to rip affordable health care away from millions and millions of Americans."

The letters come as Democrats hammer Republicans over attempts to scrap the ACA in the early days of the 2020 election, when the parties will fight for control of the White House and both chambers of Congress. The congressional GOP appears to have little appetite for reopening the Obamacare repeal fight after it lost House control last year in part due to its 2017 efforts to overhaul the health-care system.

In letters to key Trump administration officials dated Monday, Democratic House committee chairmen questioned the decision to support a lawsuit challenging the law known as Obamacare. They asked for a pile of documents from the Departments of Justice and Health and Human Services, Centers for Medicare & Medicaid Services and Office of Management and Budget related to how the White House decided to back the legal challenge and who in the administration agrees with the court's finding that the ACA is unconstitutional.

Top House Democrats are pushing the White House for more information on why it decided to back an attempt to toss out the Affordable Care Act.

Representative Jerry Nadler, a Democrat from New York and chairman of the House Judiciary Committee, speaks during a news conference on Capitol Hill in Washington, D.C., U.S., on Tuesday, April 9, 2019.

Nadler and four other committee chairmen argued in a letter to Attorney General William Barr that the decision to support the legal challenge to the ACA "appears to be violating longstanding policies to defend and enforce Acts of Congress." They said the lawsuit's success would "have a significant negative impact on the accessibility of health care for Americans."

"Finally, we are also concerned the Department's litigation posture is being driven by purely political considerations rather than considered legal arguments," wrote Nadler, House Ways and Means Committee Chairman Rep. Richard Neal, D-Mass., House Energy and Commerce Committee Chairman Rep. Frank Pallone, D-N.J., House Oversight Committee Chairman Rep. Elijah Cummings, D-Md., and House Education and Labor Committee Chairman Rep. Bobby Scott, D-Va.

Asked about the administration's reasoning during testimony before the House Appropriations Committee on Tuesday, Barr said that "when we're faced with a legal question, we try to base our answers on the law."

"I think the president has made clear that he favors not only [Obamacare's protections for people with] preexisting conditions but would like action on a broad health plan. So he is proposing a substitute for Obamacare," Barr said. He added that the replacement plan "will come if and when Obamacare is struck down."

The Department of Justice declined to comment. The Department of Health and Human Services and the Office of Management and Budget did not immediately respond to requests to comment.

Since his administration backed the challenge to Obamacare's constitutionality, President Donald Trump has repeatedly called the GOP the "party of health care" and claimed Republicans would come up with a plan to boost coverage and lower costs. However, Republicans have not yet unveiled any specific plan to replace the Affordable Care Act.

Trump had to back away from a push to replace Obamacare before the 2020 election after his own party rejected the idea. He has since said the plan would be unveiled after the election.

Republicans are, however, targeting growing Democratic calls for "Medicare for All," a government-run health care system that would cover all Americans. They argue it would cost taxpayers too much and disrupt the private insurance market.

Late last month, the Trump administration said it supports a federal judge's ruling that Obamacare is unconstitutional. An appeal of the ruling is pending in the U.S. Court of Appeals for the 5th Circuit in New Orleans.

In a filing, Justice Department lawyers said the administration "has determined that the district court's judgment should be affirmed."

Trump has pushed for years to scrap Obamacare and taken steps to weaken the law. He did so in part by signing a GOP tax bill in 2017 that got rid of the law's provision requiring most Americans to have health insurance or pay a penalty — the so-called individual mandate. The district judge ruled that absent the mandate, the entire ACA should be thrown out.

The Supreme Court likely would not rule on the Obamacare case until next year at the earliest. It has already upheld the Affordable Care Act twice.

If Obamacare gets tossed without a replacement, it would increase the number of uninsured Americans by about 32 million over a decade, the Congressional Budget Office estimated in 2017. A large chunk of the people who would lose insurance have coverage through Obamacare's expansion of Medicaid.

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