U.S. Sen. Kirsten Gillibrand called on Sunday for the full implementation of the use of a merchant category code in order to better tracking gun and ammunition sales in the United States.

A similar push to do so has been made at the state level in New York, and the use of the code has been staunchly opposed by gun dealers, who worry the move would hurt their business and the sale of legal firearms.

Still, Gillibrand on Sunday pointed to efforts needed to step up enforcement of illegal gun trafficking and more broadly curtail gun violence and mass shootings.

Democratic elected officials have called for expanded ways of combating gun violence, though laws placing restrictions on firearms have been more common on the state level in New York in recent years given the sharp partisan divide over the issue.

The code is a four-digit number designated to credit card purchases that can identify the primary business purpose. Codes have been used by the International Organization for Standardization to track purchases used by cardholders; gun purchases have typically fallen under sporting goods or miscellaneous designations.

Gillibrand wants the U.S. Department of Treasury and the U.S. Department of Justice to create a framework for financial institutions, law enforcement and dealers to help with the implementation of the merchant category code for gun and ammo pruchases. The move would result in the reporting of suspicious purchases, Gillibrand said.

“I am proud that provisions from my anti-gun trafficking bill were included in the bipartisan gun safety package, and this initiative builds on that important work,” she said. “Working with financial institutions on a new merchant category code for firearm retailers will help law enforcement monitor suspicious and possible criminal activity. I’m calling on DOJ and Treasury to help implement this new method swiftly and efficiently.”

There is skepticism and concern from gun dealers over using the codes to track purchases after state lawmakers in New York this summer pushed for similar action. Some believe more purchases would be made in cash, while at the same time raising privacy concerns.

"I do think it's going to affect us because people will be reluctant to use their credit cards; people will be afraid of what's happening," said Greg Serafini, the owner of Upstate Guns and Ammo, in an interview this summer.