Ulster Unionist MP Lady Sylvia Hermon is being asked to give assurances she would be prepared to support Conservative leader David Cameron.
Delicate negotiations are on-going which could see the UUP’s only MP being given special dispensation to run in the General Election without the formal endorsement of her party’s Conservative partners.
A key meeting of the UUP’s executive to finalise candidates for all 18 constituences, which had been expected today, has now been delayed until next week.
And the outcome of a joint UUP/Conservative committee meeting, which is also expected to deal with potential unionists pacts in South Belfast and Fermanagh/ South Tyrone, is also awaited.
But a senior UUP source said: “If this is going to work Sylvia is going to have to give assurances that if push came to shove she would support Cameron — in the event of a hung Parliament, for example.”