In a court filing late Thursday, the Trump administration is specifically urging the Texas federal court to strike down two provisions from the ACA: one that requires insurers to cover people with pre-existing conditions, and the other that prevents insurers from charging individuals a higher premium due to their pre-existing condition. It also said that provisions shielding people with medical conditions from being denied coverage or charged higher premiums and limiting how much insurers can charge older Americans should fall as well.
Many health care experts disagree with that position.
Why they did it: Republicans have targeted the Affordable Care Act for elimination ever since it passed, and President Trump continues to promise that it will be overturned. Allowing the Democratic officials to join the suit "allows us to protect the health and well-being of these Americans by defending affordable access to health care".
In the past, polls have found that both Republicans and Democrats favor protecting coverage for the tens of millions of Americans with pre-existing conditions.
The news rallied defenders of the law into action and raised questions among legal scholars about the likelihood it would succeed.
The administration does not go as far as the Texas attorney general and his counterparts. The first, known as guaranteed issue, requires insurers to offer coverage to everyone regardless of their health background.
Weighing in on a Texas challenge to the health law, the Justice Department argued that legally and practically the popular consumer protections can not be separated from the unpopular insurance mandate, which Congress has repealed, effective next year. In it, the states deem the entirety of Obamacare and its regulations invalid.
Also, 39 percent of registered voters in today's NBC/WSJ said they are enthusiastic or comfortable with a candidate seeking to repeal Obamacare, compared to 49 percent who said they have reservations or were very uncomfortable with a candidate seeking to repeal the health care law.
"There is no doubt that Republicans are responsible for the rising cost of healthcare premiums and the high likelihood that many will no longer be able to afford basic care at all, and they will face serious blowback in the midterms", the House Democrats' campaign operation said in a statement.
Sen. Susan Collins, R-Maine, who voted against the Republican repeal bills in the Senate previous year, also expressed concern about the administration's new push, saying it "creates further uncertainty that could ultimately result in higher costs for millions of Americans and undermine essential protections for people with pre-existing conditions, such as asthma, cancer, heart disease, arthritis and diabetes".
The Trump administration's move fueled accusations that it was politicizing the Justice Department, which is supposed to defend the constitutionality of federal statutes in court - even if the administration in power does not like them - if reasonable arguments can be made. "Congress has now kicked that flimsy support from beneath the law". But under the GOP tax bill signed into law last December, tax penalties for people without insurance were eliminated. Under another provision, the community rating provision, insurers were not allowed to set premiums based on a person's health history.
The 20 states that brought the lawsuit include Texas, Wisconsin, Alabama, Arkansas, Arizona, Florida, Georgia, Indiana, Kansas, Louisiana, Missouri, Nebraska, North Dakota, South Dakota, South Carolina, Tennessee, Utah, Virginia, and Gov. Paul LePage for the State of ME and Gov. Phil Bryant for Mississippi.
America's Health Insurance Plans said Friday that it plans to file a brief opposing the plaintiffs' request for emergency relief that would provides detail about the harm that would come to millions of Americans should their request to invalidate the ACA is granted either in whole or in part.
Despite the Justice Department position, the Health and Human Services Department has continued to apply the health law.
"Justice Department attorneys don't withdraw from cases simply because the government is making an argument the lawyers think the courts should or would reject", he said.
The Trump administration's move drew comparisons to the Obama administration's decision, in 2011, to stop defending the constitutionality of the Defense of Marriage Act, a law that barred federal recognition of same-sex unions that were lawful at the state level, and which the Supreme Court later struck down.
The suit is being heard by Judge Reed O'Connell, who was appointed by President George W. Bush and has ruled against the ACA in other cases the past few years.
The new challenge comes six years after the Supreme Court's divided ruling that the ACA is constitutional.