In a letter to Federal Trade Commission (FTC) Chair Lina Khan, the secretaries of state said that the deal would give a combined Kroger/Albertsons nearly a quarter of the U.S. food retail market.

"We are strongly opposed to this merger and urge you to stop this corporate consolidation that is draining Americans of their hard-earned wages and livelihoods," wrote the secretaries of state from Colorado, Arizona, Maine, Minnesota, New Mexico, Rhode Island and Vermont.

Kroger did not immediately respond to a request for comment. The FTC declined comment.

Staffers for the Federal Trade Commission, which is doing a federal antitrust probe into the deal announced in October, have reached out to experts in farming, food desserts and smaller grocery chains, according to people who spoke with the agency.

(Reporting by Diane Bartz and Jasper Ward; editing by Susan Heavey and Sharon Singleton)