An Illinois apartment owners group has sued the Centers for Disease Control over its decision to extend its moratorium on evictions, arguing that move exceeds the agency’s power and violates the U.S. Constitution.

The lawsuit by the Illinois Rental Property Owners Association, or IRPOA, follows others filed by landlord groups against the federal government since Aug. 3, when the CDC said the freeze, which expired on July 31, would continue through Oct. 3. (Read the lawsuit below.)

Housing advocates, and President Joe Biden, contend the extension is necessary to keep vulnerable renters off the streets during a pandemic—and to give states more time to distribute billions of dollars in assistance to tenants who have fallen behind on rental payments. Landlords argue the moratorium places too much of financial burden on them and encourages squatting by tenants who could pay their rent but won’t, knowing that they can’t be evicted.

Two Chicago-area apartment owners joined the IRPOA in the suit against the CDC, saying they have been hurt financially by the freeze, which has compelled them to grant rent relief to certain tenants. The trade group represents real estate investor associations with about 1,000 member landlords that own about 10,000 apartments in the state.

“The members of IRPOA’s associations range from large corporate management companies to small ‘mom and pop’ owners of duplex homes,” says the complaint, which was filed in U.S. District Court in Chicago. “Though all owners are hurt by the moratorium, the punch hits smaller owners especially.

A majority of the tenants living in the members’ buildings are protected by the moratorium because they earn less than $99,000 annually, the most they can earn to be covered by the moratorium, according to the complaint.

The CDC did not immediately respond to a request for comment.

The State of Illinois also established an eviction moratorium last year, but the freeze is set to expire at the end of August and Gov. J.B. Pritzker has said he won’t renew it.

Congress and the president have approved $46 billion in aid for apartment tenants behind on rent, a huge sum of money that should keep many renter out of eviction court. But most of the money, held up by bureaucratic delays at the state level, has yet to reach renters.

Illinois, which has received $1.5 billion from the federal government, received about 96,000 applications for assistance through its Rental Payment Program. The application process closed in mid-July, and the state had approved 22,250 applications as of Aug. 2.

It’s unclear whether the CDC’s extension of the federal moratorium will survive court challenges. A divided U.S. Supreme Court refused to suspend the ban, but Justice Brett Kavanaugh, who cast the deciding vote in that case, said he would not uphold it past July 31, unless Congress voted to continue it. At the last minute, President Biden asked Congress to extend the moratorium, deciding a few days later to extend it without Congressional action.