CHARLESTON, W.Va. — Two U.S. senators on Tuesday asked Attorney General William Barr for the Justice Department to drop its support of a ruling on the constitutionality of the federal health care law.

West Virginia Democrat Joe Manchin and Maine Republican Susan Collins sent a letter to Barr as former President Barack Obama’s healthcare law faces a challenge from a coalition of states and the Trump administration that could mean the end of the Affordable Care Act.

“Overturning the ACA will put millions of Americans and hundreds of thousands of West Virginians and Mainers at risk of losing their health insurance, including thousands of our constituents who gained health insurance through the Medicaid expansion, and thousands more who gained insurance through the ACA exchanges,” the senators said.

“With so much at stake, we urge you and the administration to reconsider this position and to defend the consumer protections for seniors, young adults, women, children, and working families.”

Judge Reed O’Connor of the District Court for the Northern District of Texas ruled in December against “Obamacare” because of its individual mandate, which required people to purchase health insurance. O’Connor said the provision, which Congress eliminated in the 2017 tax law, was essential to the healthcare law.

A coalition of states including West Virginia is arguing against the law’s legal standing. Then-Maine Gov. Paul LePage, a Republican, signed onto the lawsuit last year, yet then-state Attorney General Janet Mills declined further involvement. Mills, a Democrat, became governor in January.

The Justice Department in March came out in support of affirming O’Connor’s ruling.

Manchin and Collins told Barr millions of Americans would be at risk of losing their insurance coverage if the law is struck down, including people with pre-existing conditions and individuals who gained insurance coverage through state Medicaid expansion programs.

“It is also alarming that in the midst of the devastating opioid epidemic, millions of Americans suffering from substance use disorders would lose access to the treatment that they need to recover. It is no exaggeration to say that this is a matter of life and death to many of these Americans,” the senators wrote.

According to Manchin, around 800,000 West Virginians have a pre-existing condition. The West Virginia Department of Health and Human Resources tweeted Monday less than 156,000 West Virginians are enrolled in the state’s Medicaid expansion program.

Other individuals who would be at risk of losing their insurance coverage includes young people still on their parents’ insurance plans.

“Congress can work together to fix legislatively the parts of the law that aren’t working, but we must not let this flawed court decision stand and devastate millions of seniors, young adults, women, children, and working families,” Manchin and Collins added. “We urge the administration and the Department of Justice to reconsider the decision not to defend the critical consumer protections that have provided healthcare to millions of Americans around the country.”

Over the last year, Manchin has led multiple Democratic attempts to get the Senate Legal Counsel to intervene in the lawsuit. Manchin and Collins in 2017 opposed attempts to repeal and replace the health care law, but Collins backed a proposal giving states the option to operate under the statute.

Collins voted for the Tax Cuts and Jobs Act in December 2017, while Manchin opposed the legislation.

Both senators voted in February to confirm Barr as attorney general.

Manchin told MetroNews last month he plans to introduce with Collins a bill funding a reinsurance program for high-cost individuals. Collins previously backed a similar proposal with Florida Democrat Bill Nelson, who lost his reelection bid in the 2018 election cycle.

The state coalition and the Trump administration last week submitted briefs to the 5th Circuit Court of Appeals in New Orleans supporting O’Connor’s ruling.