Defense hawks in the Senate are in a holding pattern on a United Nations arms treaty that’s drawing strong opposition from the National Rifle Association over Second Amendment concerns.

Several influential Republican defense hawks said Thursday they have to study the issue further before signing on to oppose it, despite a loud pressure campaign from the NRA.

NRA CEO Wayne LaPierre on Wednesday told the U.N. conference negotiating the agreement that 58 senators have pledged to oppose the treaty if it covers civilian arms over fears that would infringe on the right to bear arms. LaPierre pointed to letters signed by the senators last year.