Mr Tony Blair's meetings in Belfast last night centred on continuing deadlock over future North-South bodies and the number of departments the new Assembly will operate.
The British Prime Minister held a number of meetings at Stormont with Mr David Trimble and Mr Seamus Mallon last night - but according to Mr Trimble his intervention, while welcome, has not so far resolved the differences between the North's First Minister and Deputy First Minister.
The key area of contention was the SDLP demand for a North-South trade and investment implementation body which the Ulster Unionist Party (UUP) was firmly resisting.
Mr Trimble, in his dealings with Mr Blair and Mr Mallon, insisted that there should be no mention of such an all-Ireland body in the Belfast Agreement. The UUP deputy leader, Mr John Taylor, reminded reporters that this was the SDLP proposal, which he had stated he would not touch with a "40-foot barge pole" before the signing of the Belfast Agreement.
Mr Trimble told reporters late last night that the SDLP's "elaborate and over-ambitious proposals" for a business development and inward investment North-South body were the obstacle to progress. The UUP could not agree to a body that would undermine the effectiveness of the Industrial Development Board and the other job promotion agencies in Northern Ireland, he said.
There was scope for greater co-operation but it would be unrealistic to have an all-Ireland economic agency in a situation where there were "two different countries, two different exchequers, two different fiscal systems, and two different grant structures".
Such a body would also weaken the power of the Assembly, he argued. "It is a matter of amazement that people are seriously suggesting that economic functions be extracted from the Assembly before it has even started," said Mr Trimble.
A more realistic approach from the SDLP could lead to movement. Although progress was happening "rather slowly", both sides were "getting closer to a resolution". Mr Trimble described Mr Blair's intervention as "extremely helpful".
Some senior unionists warned that the SDLP was pushing too far on the trade and investment body just as, they claimed, the nationalist demand for a Council of Ireland had undermined the Sunning dale Agreement.
Both sides are also at odds over the number of Assembly departments with the UUP favouring six or possibly seven, while the SDLP, Sinn Fein and the other parties are seeking the creation of 10 departments.
According to a senior UUP source, the UUP had agreed to the creation of an all-Ireland Irish language body, which had been proving contentious, but because the SDLP continued to press for a trade and investment body the party last night withdrew its agreement for this body.
Both sides have agreed in principle to the establishment of six implementation agencies covering transport, tourism, food safety, aqua-culture, inland waterways and marine navigation, said one senior UUP source. The economic body, the Irish language and an implementation body dealing with European Union issues were proving difficult however.
Mr Trimble earlier yesterday said that agreement was "tantalisingly" close. "We are very close to getting this sorted. It is a matter of getting things manoeuvred into the right slots, and getting the overall balance right," he added.
Mr Mallon, also speaking earlier in the day, said progress was being made. He was "still confident that before the end of the week we will have a resolution to this matter".