Oregon Attorney General Ellen Rosenblum joined attorneys general in 17 other states and the District of Columbia in a lawsuit against President Donald Trump Friday, challenging his decision to end subsidies that help keep healthcare costs affordable for low-income Americans.

The suit claims that Trump and his administration are violating the Affordable Care Act, which requires the federal subsidies by statute.

"Once again, the White House has made a rash, ill-conceived decision that will have a devastating impact on many vulnerable Oregonians," Rosenblum said in a statement. "I refuse to sit by! The President should be in the business of helping—not wrecking—Americans' financial bottom lines and access to quality health care." (Disclosure: Rosenblum is married to the co-owner of WW's parent company.)

Trump announced his decision to halt the subsidies Thursday night. The payments could stop as soon as Oct. 18, according to the U.S. Department of Justice.

Oregon joins California, Connecticut, Delaware, Illinois, Iowa, Kentucky, Maryland, Massachusetts, Minnesota, New Mexico, New York, North Carolina, Pennsylvania, Rhode Island, Vermont, Virginia, Washington, and the District of Columbia in the attempt to save the subsidies.