Updated

The families of Sept. 11 victims are voicing their opposition to a proposed change to a new law that allows them to sue Saudi Arabia for its alleged backing of the attackers.

In a statement Wednesday, they say the adjustment would "effectively gut" the Justice Against Sponsors of Terrorism Act. Saudi Arabia, a critical U.S. ally in the Middle East, sought to prevent the law from being passed.

Republicans John McCain of Arizona and Lindsey Graham of South Carolina say their measure is necessary to ensure lawsuits can only be brought against countries that knowingly engaged in the financing or sponsorship of terrorism.

But Terry Strada, national chair of a group representing Sept. 11 families, says the senators are trying to "torpedo" the law by pushing changes Saudi Arabia demanded.