Michelle Richardson, who follows national security for the American Civil Liberties Union, said his concept would be a "step in the right direction" — but also said it addresses "only a tiny slice of what's been revealed" about the agency's activities.

It's also not clear whether the proposal has any shot in Congress.

Ruppersberger said he is working with the Republican chairman of the Intelligence Committee, Rep. Mike Rogers of Michigan, and has also consulted with the White House. Ruppersberger and Rogers have worked closely together on one of the most bipartisan committees on Capitol Hill, but Ruppersberger said they are still negotiating the idea.

Without Rogers' buy-in, Ruppersberger said, "there is no bill."

Rogers' reaction, meanwhile, was noncommittal.

"I continue to work with Dutch and other colleagues in the House to craft a proposal that will address the concerns around bulk data storage, protect civil liberties, increase transparency and confidence in the government's intelligence collection activities, and maintain a targeted capability for counter terrorism operations," he said in a statement.

An NSA spokeswoman declined to comment on the proposal.

Ruppersberger, a one-time prosecutor, councilman and executive in Baltimore County, has gained national attention since becoming the Intelligence Committee's top Democrat in 2011. His district, which includes parts of Baltimore City and Baltimore, Harford, Howard and Anne Arundel counties, is home to the National Security Agency and U.S. Cyber Command.

He and many of his committee colleagues have faced criticism from some for not proposing more substantive polices to address public concern about the agency they oversee.

"There is a realignment going on," said Steven Aftergood, who writes on secrecy and security for the Federation of American Scientists.

Lawmakers steeped in intelligence issues, he said, "are facing new criticism not only from civil libertarians but also from their own congressional colleagues."

john.fritze@baltsun.com