Fire arms are seen at the Bobâs Little Sport Gun Shop in the town of Glassboro, New Jersey, United States on May 26, 2022. 

Two dozen Republican attorneys general are urging Visa, Mastercard, and American Express to abandon their plans to adopt a new merchant category code for gun retailers.

The attorneys general warned the companies that they could face legal action if they move forward with the ISO code.

The letter was signed by Tennessee Attorney General Jonathan Skrmetti and Montana Attorney General Austin Knudsen.

According to the letter, which was first reported by the Wall Street Journal, we will marshal the full scope of our lawful authority to protect our citizens and consumers.

They did not respond to the request for comment.

Senate Republicans wrote a letter to the credit card companies. The letter said that the codes are the first step towards gun control and that the companies arebowing to international and activist pressure.

The new sales code will be applied to transactions at gun stores. According to gun law advocates, a code like this is a critical first step towards giving banks and credit card companies the tools they need to recognize dangerous firearm purchasing trends and report them to law enforcement.

A merchant category code is used to indicate the type of goods sold to consumers. Gun store sales used to be categorized as general merchandise.

The new codes won't affect legal commerce according to Visa, Mastercard and American Express.

Visa said in a statement last week that it protects all legal commerce and upholds the privacy of its users. It will not change with ISO's decision.