The Republican leader of the Congressional Second Amendment Caucus says he’s disappointed in President Trump’s plan to regulate bump stocks and support legislation to boost federal background checks.

Rep. Thomas Massie, R-Ky., has argued that even the Obama administration couldn’t find a way to regulate bump stocks, which are an accessory that lets a semi-automatic weapon fire at a similar rate to an automatic weapon. He says current law doesn’t address bump stocks, which means the Bureau of Alcohol, Tobacco, Firearms, and Explosives doesn’t have the authority to regulate them.