LANSING, Mich. (AP) — Four enrollees in Michigan’s Medicaid expansion program filed a lawsuit Friday challenging work requirements that are set to take effect in January, arguing that the Trump administration lacked the authority to approve the rules that undermine the Affordable Care Act.

The lawsuit, brought in federal court in Washington, D.C., asks the judge to declare the federal approval of the requirements illegal and to block them from being implemented.

Starting Jan. 1, able-bodied adults ages 19 through 61 who want coverage in the state’s Medicaid expansion plan — Healthy Michigan — will have to show workforce engagement averaging 80 hours a month. They will be able to do so through work, school, training, substance abuse treatment or community service.

The rules could affect more than 270,000 of 670,000 participants covered by the state’s Medicaid expansion, which Michigan established under the Obama-era health law to expand coverage to low-income adults who were previously ineligible. Many expansion beneficiaries are exempt from the requirements, which also do not apply to the more than 1.7 million state residents covered by the traditional Medicaid program.