The Trump administration delivered an early midterms present to Democrats Thursday night when the Justice Department decided to side with 20 GOP states in a lawsuit seeking to gut the core protections of the Affordable Care Act for people with pre-existing conditions.

The long-shot lawsuit argues that because Republicans repealed the ACA’s individual mandate penalty as part of their tax overhaul, all of the remaining law is unconstitutional. The Justice Department, in backing the state’s argument, is seeking to strike down two of Obamacare’s most popular provisions: the rule that insurance companies can’t turn someone away or charge them more based on a pre-existing condition, and the rule that limits how much insurers can charge older patients for their premiums.

A group of Democratic state attorneys general, lead by California’s Xavier Becerra, are riding to the law’s defense.

Democrats, who were already favored going into this November’s election both on the generic ballot and on health care in particular, pounced on the news of the lawsuit, predicting “serious blowback in the midterms” for Republicans.

“This is yet another malicious Republican attack that will undermine the stability of our healthcare system, and could once again mean that you or a loved one are denied healthcare because of a pre-existing condition,” said Meredith Kelly, the communications director of the Democratic Congressional Campaign Committee (DCCC).

By Friday morning, Democratic congressional candidates were jumping on the news as well, blasting out statements slamming the administration and vowing to fight to preserve the ACA’s consumer protections.

Recent polling indicates that this could be a political winner for Democrats attempting to recapture at least one chamber of Congress.

In a CNN survey in March, 56 percent of respondents said Democrats are doing a better job on health care, while only 36 percent favored Republicans. An NBC/Wall Street Journal poll released in early June found that 36 percent people are “very uncomfortable” with a candidate who supports repealing the ACA — a significant jump up from 25 percent in 2010. And a Kaiser Family Foundation poll in May found that health care is one of the top issues on the minds of voters going into the 2018 midterms — especially Democrats.

In 2017, when Republicans in Congress attempted several times to pass bills that would have repealed the ACA’s protections with people with pre-existing conditions, there was a strong backlash, and polls found that gutting those protections was a deeply unpopular move.

More than 130 million Americans have a pre-existing condition. Should insurers win the right to once again turn those people away, the massive gains in insurance coverage under the ACA could be eroded. Additionally, even if the lawsuit is dismissed or its argument rejected by federal courts, the DOJ’s filing injects a great deal of uncertainty into the insurance market at a time when companies are right in the middle of filing their rates for 2019. Based on this development, insurers may decide to hike rates even higher or exit certain areas entirely, throwing the market further into chaos.