WASHINGTON –  A bipartisan group of 51 senators is threatening to oppose a global treaty regulating international weapons trade if it falls short in protecting the constitutional right to bear arms, as the United Nations bumps up against a Friday deadline for action. 
In a letter to President Obama and Secretary of State Hillary Clinton, the senators expressed serious concerns with the draft treaty that has circulated at the United Nations, saying that it signals an expansion of gun control that would be unacceptable.
"Our country's sovereignty and the constitutional protection of these individual freedoms must not be infringed," they wrote. 
A revised draft that circulated late Thursday of the treaty, though, raised hopes from supporters and the British government, which has been the leading proponent, that an historic agreement could be reached by Friday's deadline.
The draft closed several loopholes in the original text, though the Washington-based Arms Control Association said further improvements are still needed to strengthen measures against illicit arms transfers.
A spokesman for Britain's U.N. Mission, speaking anonymously because he was not authorized to speak publicly, said the new text is "a substantial improvement" and "an historic agreement that effectively regulates the international trade in conventional arms is now very close."