Kroger and Thomas CaldwellAlbertsons will defend their plan to merge – and try to overcome the U.S. government’s objections – in a federal court hearing scheduled to begin Monday in Oregon.

The two companies proposed what would be the largest supermarket merger in U.S. history in October 2022. They say joining together would help them rein in costs and better compete with big rivals like Walmart and Costco.

But the Federal Trade Commission sued to try to block the deal, saying it would eliminate competition and raise grocery prices in a time of already high food price inflation. The commission also alleged that quality would suffer and workers’ wages and benefits would decline if Kroger and Albertsons no longer competed with each other.

The FTC is seeking a preliminary injunction that would block the merger while its complaint goes before an in-house administrative law judge. In a three-week hearing set to begin Monday, U.S. District Judge Adrienne Nelson is expected to hear from around 40 witnesses, including the CEOs of Kroger and Albertsons, before deciding whether to issue the injunction.

The attorneys general of Arizona, California, the District of Columbia, Illinois, Maryland, Nevada, New Mexico, Oregon and Wyoming all joined the case on the FTC’s side.

Kroger, based in Cincinnati, Ohio, operates 2,800 stores in 35 states, including brands like Ralphs, Smith’s and Harris Teeter. Albertsons, based in Boise, Idaho, operates 2,273 stores in 34 states, including brands like Safeway, Jewel Osco and Shaw’s. Together, the companies employ around 710,000 people.