The House Judiciary Committee postponed a scheduled Tuesday markup on a resolution to nullify a Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) pistol brace rule following the mass shooting at a Nashville, Tennessee, school on Monday.

“Democrats were going to turn this tragic event into a political thing,” Judiciary Committee Chair Jim Jordan (R-Ohio) told The Hill on Monday evening.

Punchbowl News first reported that the hearing would be postponed.

Police said a 28-year-old woman killed three nine-year-olds and three adult staff members at Covenant School, a private Christian school in Nashville, on Monday. Authorities said the shooter had assault-style weapons and a handgun.

The ATF rule that Republicans are seeking to nullify would reclassify pistols that have a stabilizing brace as short-barreled rifles, and require those with existing pistols that have stabilizing braces to register with the government by May 31, 2023.

“This issue we wanted to mark up tomorrow that we’ll mark up here in a couple of weeks as is all about the Constitution,” Jordan said. “You had an agency tell Americans the rule was one thing. Ten years later, they just changed the rule without going through Congress. So, this is a Constitutional concern, but Democrats had already been talking about making everything political, so we just decided to postpone.”

The Justice Department in announcing the rule said that the new regulation ensures that manufactures, dealers, and individuals who use stabilizing braces to convert pistols into rifles with a barrel of less than 16 inches should comply with the laws of short-barrel rifles. That marks a change from 2012, when the ATF said pistol attachments do change the classification of a pistol.

“In the days of Al Capone, Congress said back then that short-barreled rifles and sawed-off shotguns should be subjected to greater legal requirements than most other guns. The reason for that is that short-barreled rifles have the greater capability of long guns, yet are easier to conceal, like a pistol,” ATF Director Steven Dettelbach said in a statement in January. “But certain so-called stabilizing braces are designed to just attach to pistols, essentially converting them into short-barreled rifles to be fired from the shoulder. Therefore, they must be treated in the same way under the statute.”