The initiative, which has the backing of British ministers, could help to break one of the most difficult deadlocks in the peace negotiations by providing Sinn Fein with an incentive to enter full democratic politics.
The US Ambassador to London, Admiral William Crowe, has met the Sinn Fein President, Gerry Adams, to discuss the proposal, which opens up the chance of tapping a potentially huge source of funds.
The dialogue between the British Government and Sinn Fein, which will resume on Wednesday, has been making slow progress. The issues of arms and the release of prisoners - now complicated by the review of Private Clegg's case - are seen as two crucial obstacles on the road to permanent peace.
Both may have to be addressed in exploratory talks before Sinn Fein can be admitted to the peace process.
In private discussions, Admiral Crowe has told Mr Adams that the ban on fund-raising in the US will be lifted if progress is made on arms. British ministers say the Americans' role has been "helpful".
For more than a year Mr Adams and colleagues have been allowed visas to visit the United States but prevented from fund-raising. The lifting of this ban might well provide the resources for Mr Adams and his colleagues to transform their party into a powerful political force in Northern Ireland. It would also give Sinn Fein much-sought international credibility.
The British government has been anxious not to box in Sinn Fein and the IRA over arms. Ministers concede that it is not realistic to expect that all arms, weapons or explosives will be surrendered. Instead the security forces would need to be satisfied that sufficient quantities had been "decommissioned'' to prove that the IRA is serious.
The Government has also been careful to call for progress on "the issue" of decommissioning. That opens up the prospect of a timetable under which weapons would be handed over as talks start, rather than as a precondition of them taking place.
However it remains unclear that any significant progress has so far been made. Sinn Fein has not, publicly, said that it has any influence over the IRA, although British sources suggest that has been admitted in private.
Yesterday Sinn Fein made clear their disquiet at the prospect of the release of Private Clegg, the soldier convicted of murder while serving in Northern Ireland, if Republican prisoners remain in jail.
Mainland pressure for Private Clegg's release, supported by dozens of Conservative MPs, has presented the Northern Ireland Office with a dilemma. Sir Patrick Mayhew, Secretary of State for Northern Ireland, has written to MPs explaining that a quasi-judicial process is taking place.
However he is aware that any decision to release Private Clegg on licence will complicate exploratory negotiations with Sinn Fein. Republicans argue that this is the same mechanism which could be used for their prisoners, and Loyalists, in Northern Ireland.
Government sources believe that a decision on Private Clegg's case is unlikely this week.
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