TOPEKA, Kan. (AP) — A federal judge in Kansas has refused to block the nationwide enforcement of a Biden administration rule requiring firearms dealers to do background checks of buyers at gun shows, leaving Texas as the only state so far where a legal challenge has succeeded.

U.S. District Judge Toby Crouse’s ruling this week came in a lawsuit brought by Kansas and 19 other states, three individual gun collectors and a Wichita, Kansas-based association for collectors. They sought an order preventing the Bureau of Alcohol, Tobacco, Firearms and Explosives from enforcing the rule that took effect in May through the trial of their lawsuit.

Twenty-six states with Republican attorneys general, gun owner groups and individual gun collectors filed three federal lawsuits in May against the Biden administration. The rule is an attempt to close a loophole allowing tens of thousands of guns to be sold every year by unlicensed dealers without checks to see whether buyers are legally prohibited from having firearms. It applies not only to gun shows but also to other places outside brick-and-mortar firearms stores.

Critics contend the new rule violates gun rights protected by the Second Amendment and that Democratic President Joe Biden’s administration doesn’t have the legal authority to issue it. They also argue that the rule will depress gun sales, making firearms less available to collectors and costing states tax revenues.

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But Crouse, an appointee of former President Donald Trump, said in his ruling Wednesday that predictions of harm to the states, gun collectors and groups are too speculative and create doubts that they actually have grounds to sue. He said such doubts undermine their argument that they are likely to win their lawsuit — a key question for the courts in deciding whether to block a rule or law ahead of a trial.

“While they may ultimately succeed on the merits, they have failed to make a strong showing that they are substantially likely to do so,” Crouse wrote.

Crouse’s ruling contrasts one from another Trump appointee in Texas before the rule took effect. U.S. District Judge Matthew Kacsmaryk blocked its enforcement in that state and against members of four groups, including Gun Owners of America. But Kacsmaryk didn’t block it in three other states that joined Texas in its lawsuit — Louisiana, Mississippi and Utah.

Florida filed a lawsuit in federal court there, but a judge has yet to rule.

The states also sued U.S. Attorney General Merrick Garland, the U.S. Department of Justice and the ATF’s director. The DOJ declined to comment Friday on Crouse’s ruling.

Phil Journey, one of the gun collectors involved in the Kansas case, said he doesn’t know whether Crouse’s ruling will be appealed.

“I am confident the rule and perhaps the underlying statute will ultimately be voided,” Journey, a former Kansas state senator who’s now a state district court judge in Wichita, said in a text.

Kansas Attorney General Kris Kobach also said in a statement that he expects the rule ultimately to be struck down.

“This is a very early stage in a case that is likely to continue for a long time unless President Trump is elected and immediately rescinds the rule,” Kobach said.

In the lawsuit before Crouse, Kansas was joined by Alabama, Alaska, Georgia, Idaho, Indiana, Iowa, Kentucky, Montana, Missouri, Nebraska, New Hampshire, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Virginia, West Virginia and Wyoming.

The lawsuit originally was filed in federal court in Arkansas, with that state also suing. But in ruling just days after the rule took effect, U.S. District Judge James Moody Jr., an appointee of former President Barack Obama, said Arkansas had no standing to sue because its argument that it could lose tax revenue was too speculative. Moody then transferred the case to Kansas.