After  its merger announcement over a year ago, the Kroger-Albertsons unification  faced multiple protests regarding fair competition, potential layoffs and price surges. 

Now, a group of U.S. lawmakers sent a letter to the Federal Trade Commission (FTC) citing “the negative impacts the merger would have on consumers, workers, and the grocery industry as a whole,” Supermarket News reports.

The letter was signed by Sens. Elizabeth Warren, Mazie Hirono, Bernie Sanders, and Cory Booker along with representatives Summer Lee and Alexandria Ocasio-Cortez.

This isn’t the first time the FTC has been involved in objecting to the acquisition. Not long after the merger was first announced, the commission put the deal on hold.

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Detractors then demanded that Albertsons Cos. delay paying a $4 billion dividend to investors until after the merger is reviewed by the federal entity.

As the first concerns were raised, the grocers put in place divestiture strategy, aiming to relieve skepticism from antitrust regulators. The plan included the sale of over 400 C&S Wholesale Grocers stores for nearly $2 billion.

In November, Kroger assured the FTC that it had met all antitrust law requirements. The FTC has until Dec. 15 to decide on the merger.

The $25 billion deal would bring together more than 2,700 Kroger stores across the U.S. and over 2,200 Albertsons locations.