Senate supporters of the so-called media-shield bill said the deal would give the government authority to override those rights in certain national security cases.

Sen. Charles E. Schumer (D., N.Y.) said the agreement "strikes the right balance between national security concerns and the public's right to know." He said it would preserve a strong defense for reporters trying to protect sources while making sure the government can do its job of protecting citizens.

The Senate Judiciary Committee could take up the altered legislation next week.

Lucy Dalglish, executive director of the Reporters Committee for Freedom of the Press and a member of the media team involved in the talks, said: "I think it is a compromise we can live with, and it seems to be a compromise the White House can live with. It's certainly better than the status quo."

The House passed its version of a media-shield bill in March, but the measure has stalled in the Senate and took a step back last month when the administration unexpectedly sought to broaden government authority to compel testimony. Dalglish said that approach was "quite honestly a slap in the face."

Schumer met with Attorney General Eric H. Holder Jr. last month to try to find common ground, Schumer's office said.

The original bill centered on the idea that a balancing test should be applied under which a federal judge would weigh the public's right to know vs. national security claims made by the government. The administration wanted to eliminate that balancing test in many cases involving terrorism and other security cases.

Under the compromise, the balancing test would be eliminated in cases of a classified leak in which the government can show that disclosure of a source's identity is necessary to prevent or mitigate an act of terrorism or substantial harm to national security.

But the government would also have to provide specific facts: It could not make a national security claim and then withhold most of the details.

The balancing test would be in order for cases not involving classified leaks, but in criminal cases the burden would be on the journalist to show clear and convincing evidence that guarding the anonymity of sources is in the public interest.

In noncriminal cases the government would bear the burden in proving that compelling disclosure of a confidential source outweighs the public interest in newsgathering.

"The negotiated compromise creates a fair standard to protect the public interest, journalists, the news media, bloggers, prosecutors, and litigants," said Sen. Arlen Specter (D., Pa.), a cosponsor of the bill.

The revised bill would also extend protections for freelance or citizen journalists by defining a journalist by the nature of activity engaged in rather than by the organization that employs the reporter.

Protections in the bill apply not only to information held directly by reporters but also to reporter information such as phone and e-mail records held by third-party service providers.