The Trump administration isn’t defending key parts of the Affordable Care Act from a legal attack that could finally slay the ACA individual major medical market framework, but the federal government cautioned Wednesday that an immediate and nationwide halt may trigger “chaos.”

(Related: Anti-ACA Lawsuit Puts GOP on Defensive Before Elections)

Unlike the state of Texas, which urged a federal judge to block the Affordable Care Act as a whole right away, the Justice Department wants the court to split off the ACA individual major medical mandate and ACA coverage pricing rules from the rest of the law.

The department also wants a court order affecting the mandate and the pricing rules not to take effect before Jan. 1, when the ACA penalty on many people who fail to have what the government classifies as solid major medical coverage goes away.

Blocking those key ACA provisions before January would “cause chaos in the insurance market,” Deputy Assistant Attorney General Brett Shumate told U.S. District Judge Reed O’Connor.

While the federal government’s position has been consistent since it first announced in June that it won’t defend the ACA individual mandate and the ACA price rules, the politics around the Republican-led effort to nullify the ACA have been amplified in the run-up to the November congressional elections.

Wednesday’s court arguments come as Republicans try to defend their control of the House and Senate while many Democrats make health care a central issue in their campaigns.

O’Connor asked tough questions of all sides, including a group of Democratic attorneys general who’ve stepped in to defend the ACA, and didn’t signal how he will rule.

—With assistance from Sahil Kapur and Kartikay Mehrotra.

— Read GOP’s Obamacare Suit May Strengthen the Lawon ThinkAdvisor.

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