LITTLE ROCK, Ark. (AP) — Twenty-six Republican attorneys general filed lawsuits Wednesday challenging a new Biden administration rule requiring firearms dealers across the United States to run background checks on buyers at gun shows and other places outside brick-and-mortar stores.

The lawsuits filed in federal court in Arkansas, Florida and Texas are seeking to block enforcement of the rule announced last month, which aims to close a loophole that has allowed tens of thousands of guns to be sold every year by unlicensed dealers who do not perform background checks to ensure the potential buyer is not legally prohibited from having a firearm.

The lawsuit argues the new rule violates the Second Amendment of the U.S. Constitution and that Democratic President Joe Biden doesn’t have the authority to implement it.

“Congress has never passed into law the ATF’s dramatic new expansion of firearms dealer license requirements, and President Biden cannot unilaterally impose them,” Arkansas Attorney General Tim Griffin said in a statement. “This lawsuit is just the latest instance of my colleagues in other states and me having to remind the President that he must follow the law.”

The Bureau of Alcohol, Tobacco, Firearms and Explosives and the Department of Justice declined to comment on the lawsuit. Biden administration officials have said they are confident the rule, which drew more than 380,000 public comments, would withstand lawsuits.

As the 2024 presidential campaign heats up, the lawsuit and potential court battle to follow could animate both sides — GOP voters who want fewer restrictions on guns and Democrats who want more restrictions on types of firearms and access to them.

Biden has made curtailing gun violence a major part of his administration and reelection campaign as the nation struggles with ever-increasing mass shootings and other killings. He created the White House Office of Gun Violence Prevention, overseen by Vice President Kamala Harris, and has urged Congress to ban so-called assault weapons — a political term to describe a group of high-powered guns or semi-automatic long rifles, like an AR-15, that can fire 30 rounds fast without reloading. Such a ban was something Democrats shied from even just a few years ago.

Gun control advocates have long pushed for closing the so-called gun show loophole and have praised the new rule on background checks.

“If we don’t update our national system by closing these loopholes, there is no telling how many more Americans we will lose to gun violence,” said Kris Brown, president of the gun control group Brady. “Brady will do everything in our power to defend this rule because we know it brings us closer to a future free from gun violence.”