A key Republican and Democrat in the Senate are attempting to find a bipartisan compromise on gun control legislation that would make it harder for people on the federal terror watch list to purchase firearms or explosives.

Senate Majority Whip John Cornyn, R-Texas, and Sen. Dianne Feinstein, D-Calif., are seeking a legislative middle ground between Cornyn’s bill, which would impose a three-day delay for those on the list, and Feinstein’s bill, which would ban people on the terror watch list from buying guns.