FORT WORTH — Lawyers with the state of Texas urged a federal judge on Wednesday to immediately overturn the Affordable Care Act in its entirety, a request the federal government warned could sow confusion and create turmoil in state health insurance markets.

Texas Attorney General Ken Paxton, a Christian conservative who's up for re-election this year, is suing the Trump administration on behalf of 20 Republican state officials who want an immediate and nationwide halt to Obamacare. The administration agrees that parts of the law are unconstitutional. But inside the courthouse on Wednesday, lawyers with the U.S. Department of Justice said the federal government doesn't want the law axed immediately.

"The department opposes any nationwide injunction," Justice Department Deputy Assistant Attorney General Brett Shumate said. An immediate halt, he warned, "could throw the health care markets into chaos."

U.S. District Court Judge Reed O'Connor did not make an immediate decision on the injunction Wednesday. But after questioning all sides extensively, he promised to issue a ruling "just as quickly as I can." He has many options, including honoring the Texas coalition's request to throw out Obamacare immediately, a decision guaranteed to trigger an appeal.

'A potential for chaos'

Paxton is no stranger to suing the federal government. He's filed dozens of lawsuits since being sworn in as attorney general in January 2015, and has continued to sue the Trump administration to push them to overturn Obama-era rules or enact more conservative policies on issues like immigration and the environment.

Paxton's coalition filed its Obamacare lawsuit in February, just a couple of months after Congress axed the tax the health care law required people to pay if they didn't have insurance. The coalition argued since this individual mandate penalty would be gone beginning Jan. 1, 2019, then the constitutionality of the entire law should also be in question.

Then, last month, Paxton wrote that even if O'Connor does not strike down all of Obamacare, he should invalidate its protections for pre-existing conditions because they are "closely intertwined" with the individual mandate. Without one, he argued, the other won't work.

On Wednesday, Paxton's deputy made this argument in O'Connor's court. He said the health care law is unconstitutional and argued states — not the federal government — should decide whether insurance companies must cover people with pre-existing conditions like asthma and cancer. Not halting Obamacare, he said, would cause "irreparable harm" to states by subverting their sovereignty and increasing the number of people on their insurance rolls.

"The ACA will continue to cause these harms as long as it operates," said Darren McCarty, an assistant attorney general for the state of Texas, adding the court should "restore choice to state health insurance markets."

1 / 5Cary Clark of Fort Worth dressed as the grim reaper for a protest opposing Texas' attempts to overturn the Affordable Care Act, known as Obamacare, and its protections for people with pre-existing conditions outside the Eldon B. Mahon Courthouse in Fort Worth on Wednesday, Sept. 5, 2018.(Lauren McGaughy / The Dallas Morning News) 2 / 5Alejandrina Guzman, left, stands with Justin Nelson and Beverly Powell protest Texas Attorney General's lawsuit to overturn the Affordable Care Act, or Obamacare, outside the Eldon B. Mahon Courthouse in Fort Worth on Wednesday, Sept. 5, 2018. Nelson is challenging Paxton and Powell is running for Texas Senate. Both are Democrats.(Lauren McGaughy / The Dallas Morning News) 3 / 5Attorney General Ken Paxton prepares to speak at a Collin County Republican Party event Monday, September, 3, 2018 in McKinney, Texas. (Ryan Michalesko/The Dallas Morning News)(Ryan Michalesko / Staff Photographer) 4 / 5Robert Henneke, General Counsel, Director, Center for the American Future talks to the media the Affordable Care Act at Eldon B. Mahon U.S. Courthouse in Fort Worth, TX, Wednesday, Sept. 5, 2018. On Wednesday, Texas Attorney General Ken Paxton's proposal to repeal the Affordable Care Act is scheduled for a 9:30 a.m. hearing before U.S. District Judge Reed OÃConnor. (Max Faulkner / The Fort Worth Star-Telegram) 5 / 5Michael Lummus, Alvarado, TX, talks to the media about his reliance on the Affordable Care Act at Eldon B. Mahon U.S. Courthouse in Fort Worth, TX, Wednesday, Sept. 5, 2018. On Wednesday, Texas Attorney General Ken Paxton's proposal to repeal the Affordable Care Act is scheduled for a 9:30 a.m. hearing before U.S. District Judge Reed OÃConnor. (Max Faulkner / Fort Worth Star-Telegram)

The Trump administration's lawyer agreed that protections for pre-existing conditions "cannot function" without the individual mandate penalty. But he stopped short of saying the entire law is invalid and urged O'Connor not to grant Texas' calls for an immediate injunction.

"There could be a potential for chaos," Shumate said. Many state health insurance marketplaces don't close until December or January, and he argued turning the entire health care system on its head before then would create confusion among those actively seeking insurance.

Since the federal government has decided not to defend Obamacare in its entirety, a group of Democratic attorneys general have stepped in to do so. On Wednesday, they argued that overturning the law would result in tens of millions of Americans losing their health insurance. More than 52 million non-elderly Americans have pre-existing conditions that could result in them facing difficulty obtaining insurance if Obamacare is overturned, according to the Kaiser Family Foundation.

"Six million of their residents would be kicked off their Medicaid. ... And millions of residents with pre-existing conditions would not be able to purchase or access health care," California Deputy Attorney General Neli Palma told O'Connor. "The plaintiffs aren't seeking to maintain the status quo. They're seeking to blow it up."

The team from California also cited multiple Republican lawmakers who've pushed back against the suit, including U.S. Lamar Alexander of Tennessee, who called it "as far-fetched as any I've ever heard."

But the solicitor general of Wisconsin, a state that has joined with Texas in the lawsuit, said there was no "disastrous hellscape" to come if Obamacare was halted, and called California's arguments "irrational" and "irrelevant."

"The entire ACA should fall," Misha Tseytlin told O'Connor. Without the individual mandate, he said, the law is nothing more than a "hollow shell."

'An embodiment of pre-existing conditions'

Outside the courthouse, a few dozen people gathered to protest Paxton's decision to file the lawsuit. Led by the attorney general's Democratic opponent, Justin Nelson, they chanted, "Hey hey, ho ho, Ken Paxton has got to go!"

After the hearing, Paxton issued a statement arguing Obamacare "was only tethered to the Constitution by a very thin thread." But he did not attend the arguments himself, a decision his opponent — who watched them from an overflow room courthouse — said were tied to the attorney general's personal legal troubles.

Paxton was indicted in July 2015 of three felonies, two first-degree fraud charges and one third-degree charge for failing to register as an investment adviser representative. His trials, which will take place in Houston, are on hold and unlikely to be held before Election Day on Nov. 6.

"This lawsuit is nothing more than a distraction — a distraction that Ken Paxton is trying to do from his own indictment for fraud," Nelson told the crowd outside the courthouse. "Ken Paxton is not here today. ... Ken Paxton does not have the guts."

Of the 52 million non-elderly Americans with pre-existing conditions, about 20.7 million live in the 20 states in Paxton's coalition. Around 4.5 million of them are Texans, according to the Kaiser Family Foundation.

One of those Texans is Alejandrina Guzman, who was born with diastrophic dysplasia, a disorder that causes dwarfism and other physical developmental problems. Guzman, who served as the University of Texas at Austin's first Latina student body president, sat beside Nelson on Wednesday and called herself "an embodiment of pre-existing conditions."

"I'm outraged, to say the least," Guzman said. "I can't imagine not having that access. And that's just my story. That's just me — one individual."