CNN says the United States has proposed sending former Vice President Al Gore or New Mexico Governor Bill Richardson to Pyongyang to negotiate the release of two detained American journalists.

The report quoted several senior administration officials as saying the idea of sending either Gore or Richardson to Pyongyang on a mission to negotiate the journalists’ release has been floated to the North Koreans.

The report said that although North Korea has thus far neglected to respond to the idea, the expectation has been that once the trial has ended, the North would accept a visit by either Gore or Richardson to secure the journalists' release.

CNN, however, stopped short of elaborating on the channel through which Washington made the proposal.

Earlier on Sunday, Secretary of State Hillary Clinton said during an interview with ABC News that she had sent a letter to Pyongyang asking for the release of Laura Ling and Euna Lee.

Gore is the head of San Francisco-based Current TV --- the media organization for which Ling and Lee work.

Richardson has, in the past, successfully negotiated the release of other Americans detained by North Korea.