Mr David Trimble is believed ready to serve in Mr Iain Duncan Smith's shadow cabinet as part of a Westminster coalition between the Ulster Unionists and British Conservatives.
It is understood the two leaders agreed some kind of pact "in principle" at a meeting in the Conservative leader's House of Commons office last Tuesday.
However, while their negotiations are continuing, it is not certain that Mr Trimble can win the backing of a majority of his MPs for such a development, at least at this time.
Moreover, some traditional Trimble loyalists in the pro-Belfast Agreement camp are strongly opposed to any formal relationship in the House of Commons which might be intended to lead to an eventual merger between the two parties.
While reluctant to discuss the matter at all yesterday, Mr Trimble responded to reports of his talks with Mr Duncan Smith by insisting there was "no question of a merger".
Mr Trimble also dismissed suggestions in the Mail on Sunday that a coming together of the two parties could actually set him on course to succeed Mr Duncan Smith as Conservative leader.
Of this and similar speculation in the past, Mr Trimble said: "I have smiled indulgently at people who have raised this fantasy, but I do not treat it seriously. I am certainly not engaged in some devious plot to manoeuvre myself into such a position."
Mr Trimble's sensitivity on this point reflects an acute awareness that some of his opponents are happy to portray his enthusiasm for a new alliance with the Conservatives in terms of perceived personal ambition and a desire to secure an influential role for himself beyond Northern politics.
More importantly, he would see this as a gross distortion of a serious political project by which he thinks to extend unionism's influence and to protect it against Sinn Féin's insistence that the Belfast Agreement is but the transitional route to a united Ireland.
The proposed realignment of Conservative and unionist forces - first revealed in The Irish Times last summer - reflects Mr Trimble's determination to "put Ulster unionism at the heart of British politics".
Despite opposition from MPs and senior party officers when the idea was first mooted, the UUP leader appears to have intensified his efforts to effect a new alliance following the suspension of the North's Assembly.
Under the terms of an outline approach discussed with Mr Duncan Smith last week, the UUP might hope to gain two additional posts on the opposition front bench at Westminster.
However, there is surprise bordering on disbelief that Mr Trimble could think to resume office as First Minister in any restored Executive while also serving, possibly even as Northern Ireland spokesman, as a member of the shadow cabinet in London.
One Ulster Unionist MP has said privately he will reserve his position on the proposed realignment until he learns whether Mr Trimble is actually developing "an alternative political strategy" based on the assumption that the current intensive negotiations designed to restore the Assembly will fail.
There is no evidence of any such assumption informing Mr Trimble's thinking. To the contrary, one supporter last night suggested that a beneficial consequence of a renewal of the UUP/ Conservative relationship might be to strengthen bipartisanship at Westminster if and when the Ulster Unionists decided to rejoin the power-sharing Executive.
It is thought the Conservative spokesman on Northern Ireland, Mr Quentin Davies, has not been party to the discussions between his leader and Mr Trimble.