Under federal law, people who pose a heightened risk of violence cannot buy or own firearms, including convicted felons, domestic abusers, the seriously mentally ill and several other categories. Suspected terrorist is not one them.

Individuals on the government’s terrorist watch list can be barred from boarding airplanes, but not from purchasing high-powered guns or explosives. Bipartisan legislation in both houses of Congress would end this ridiculous loophole, commonly known as the “terror gap.”

Introduced in the Senate by Frank Lautenberg, a New Jersey Democrat, and in the House by Representative Peter King, a Republican of Long Island, this reform was first offered in 2007 with support from the Bush administration, a rare departure from the gun lobby’s party line. The Obama administration has endorsed the bill.

This is no small problem. An audit by the Government Accountability Office released last June found that since 2004, people on the terrorism watch list succeeded in purchasing firearms 865 times in 963 attempts. The relatively few denials owed to another factor like a felony conviction. A 2005 G.A.O. review found people on the watch list were able to buy weapons in 35 of 44 attempts between February 2004 and June 2004.