Ulster Unionist leader Mr David Trimble proposed that he and SDLP leader Mr Mark Durkan should serve as British direct rule ministers during the suspension of the Northern Ireland Assembly.
Mr Trimble made his radical suggestion during talks with Downing Street officials in the week before Monday's suspension of the devolved government at Stormont.
However The Irish Times understands the idea - which would have required both men to take the British Labour Party whip, and serve as junior ministers in the Stormont administration under Secretary of State Dr John Reid - was flatly rejected by the SDLP leader.
Confirmation of Mr Trimble's willingness to serve as a member of the Blair government - albeit for a limited time and specific purpose - will surprise Ulster Unionists gathering today for their annual party conference, to be addressed by the leader of the British Conservative Party, Mr Iain Duncan Smith.
During the past year Mr Trimble has similarly surprised his senior party officers with a proposal to renew the formal relationship between the Ulster Unionists and the Conservatives.
Sources close to the UUP leader say he believes the appointment of himself and Mr Durkan as ministers would have "kept alive the spirit of devolution" following the British Government's reluctant suspension of the Assembly and power sharing Executive as a result of alleged IRA espionage at the heart of the Northern Ireland Office.
It also seems clear Mr Trimble considered this superior to an alternative plan for him and Mr Durkan to lead a "shadow administration" to advise Direct Rule ministers during suspension - a proposal he understood agreed "in principle" with the SDLP leader before Mr Durkan came under Dublin pressure to reject it.
Confirming that the possibility of appointing the two men ministers was discussed by Mr Trimble with Number 10, one British source last night suggested "it was no more than an idea".