Steve Dettelbach says he does want to ban “assault weapons” even though he does not have a working definition of which guns would fall under such a ban.

The ATF director nominee told Senator Tom Cotton (R., Ark.) he could not explain which guns he believed should be banned. In an exchange during his Wednesday confirmation hearing in front of the Senate Judiciary Committee, Dettelbach said he hasn’t attempted to define the category of guns he hoped to ban. Instead, he said Congress should decide on the definition.

“When I was a candidate for office, I did talk about restrictions on assault weapons,” Dettelbach said. “I did not define that term. And I haven’t gone through the process of defining that term. That would only be for the Congress if it chose to take that up to do.”

Dettelbach’s hearing comes just a day after the horrific massacre at Robb Elementary School in Uvalde, Texas, where a gunman murdered 19 children and two teachers. President Joe Biden (D.) has argued he needs a permanent ATF director to help institute his plan to reduce gun violence. The President has also called on Congress to institute a new assault weapons ban in the wake of the shooting.

The same asault weapon question tripped up President Biden’s previous ATF director nominee, David Chipman, at his confirmation hearing a year ago. Chipman had also advocated for an assault weapons ban but was unable to define the term. His nomination ultimately failed in the evenly divided Senate as several Democratic senators refused to back him after he was involved in numerous controversies.

Dettelbach faces the same Senate but with more support from former ATF directors and a potentially less-polarizing history. While Dettelbach was endorsed by Everytown for Gun Safety, a gun-control group, during his 2018 run for Ohio Attorney General, Chipman spent much of his career as an employee of several gun-control groups. Dettelbach also faced less scrutiny from Senators about his past comments than Chipman did.

Dettelbach’s history of questioning the validity of Ohio’s elections was not brought up at the hearing. Neither were comments from the National African American Gun Association questioning why Biden picked him over a qualified Black acting director. However, his inability to define assault weapon was a sticking point for Senator Cotton.

“So, you were running for public office, and you called for a ban on assault weapons, but you don’t have a definition for assault weapons?” Cotton asked.

“Senator, it would only be for a legislative body, whether it was the Ohio legislature or the Congress, it would only be for a legislative body to do that work,” Dettelbach replied.

Dettelbach said he understood defining “assault weapon” would be a “difficult task.” He said the goal should be to make a ban broad enough to avoid becoming “meaningless” but not “so broad as to infringe on the rights of law-abiding Americans unnecessarily.” He offered to help guide Congress in the process.

“If you chose to take it up, I would be at the ATF, and there’s perhaps expertise or data we could give you so that you could make the appropriate decision to both protect the public and protect the Second Amendment,” he said.

Cotton followed up by asking Dettelbach if he was familiar with the definition used under the 1994 federal assault weapons ban. That ban made it illegal to sell any semiautomatic firearm that could accept detachable magazines and had two or more banned features, such as a pistol grip or telescoping stock. Dettelbach said he had not looked at that definition.

“I don’t know enough about that,” he said. “That’s a definition that I’m not particularly familiar with. And I haven’t studied the data on how on that particular definition. I’ve heard comments on both sides of that, Senator. I acknowledge that’s a very difficult issue. That is for this body to decide.”

Cotton said Dettelbach’s inability to define assault weapon is evidence it’s a nebulous term invented by “politicians and lawyers in Washington.” He said the term is political and not based on a real class of firearms.

“I think it’s very telling that you’re nominated to leave the ATF, and you don’t have a definition of assault weapon,” he said. “Point is that there is really no such thing as a category of weapons known as assault weapons. There are rifles or shotguns; there are pistols. They have properties. They have features. But there is no such thing as a category of assault weapons.”

Dettelbach will now face written questions from the committee members before moving to a vote on whether to recommend him for a full floor vote.