Nearly two dozen Republican Attorneys General have signed on to a letter being sent to Visa, Mastercard, and American Express that urges the companies to rescind their plans to use new merchant category codes that will identify purchases made at gun stores, warning that the new codes “unfairly singles out law-abiding merchants and consumers alike.”

The Wall St. Journal, which broke the news about the letter, reports that it the effort is being spearheaded by Tennessee Attorney General Jonathan Skrmetti and Montana Attorney General Austin Knudsen, but 21 other GOP AGs have joined the pair in demanding that the companies back off their announced plans to adopt the new codes.

Gun-control advocates have pressed the financial industry to do more to help curb mass shootings, though it has been an uphill climb. They say the new merchant code could help identify suspicious gun sales.

Gun-rights advocates have long resisted such efforts, saying they could unfairly prevent legal gun purchases.

In interviews, both Mr. Knudsen and Mr. Skrmetti said they could launch investigations into the companies if they moved forward with the gun-shop code.

“We will marshal the full scope of our lawful authority to protect our citizens and consumers from unlawful attempts to undermine their constitutional rights,” their letter said.

Merchant codes generally don’t identify the product a card user is buying. Instead, they describe the type of store where a purchase was made. That means transactions with the gun-shop MCC might involve gun purchases, hunting gear or a gun safe, among other things.

The payments industry has long been divided on whether to assign MCCs to gun shops. Some executives have privately flagged concerns that it could lead to the creation of more codes for cracking down on businesses such as abortion providers.

Visa, Mastercard and Amex say the new merchant code will function just like others and won’t stop gun purchases from happening. The companies say they won’t allow purchases to be blocked based solely on the merchant code.

“We do not believe private companies should serve as moral arbiters,” Visa said in a post last week.

“If we identify unauthorized blocking or intentional restrictions of legal commerce, we will take swift action to address such activity,” Mastercard said recently.

While it’s been good to see companies like Mastercard and Visa throw a little cold water on the gun control lobby’s next steps in their plan to use the financial services industry to attack the right to keep and bear arms over the past few days, it’s just as gratifying to see the response by many Republican officials. GOP members of Congress have already sent a letter of their own to the firms asking them how “suspicious purchases” will be identified and flagged for law enforcement, but the warning by the Attorneys General may have an even bigger impact on these companies moving forward.

Anti-gun activists and politicians were clearly hoping to build on their pressure campaign aimed at Visa, Mastercard, and American Express by demanding companies start actually tracking and identifying specific purchases made at gun stores, but given the companies’ statements in the wake of the new MCCs being adopted, I think the pro-2A counter-campaign is making a difference, and the coming demands are more likely to meet with resistance now that Second Amendment supporters are clued in to what this effort is really all about.