Mr Richard Haass, the US special envoy, has begun what is expected to be his final round of talks with the Northern parties in Belfast.
He met the leaders of Sinn Féin and the SDLP in Belfast last night, and is due to talk to both the DUP and the Ulster Unionists this morning. He will then go to Dublin to meet the Taoiseach, Mr Ahern, and the Minister for Foreign Affairs, Mr Cowen.
Mr Haass is not due to make any comments until later today when he hosts a press conference. However, he indicated last night that the Assembly election results should not provoke pessimism.
Speaking in Belfast on his way into the US consulate yesterday, Mr Haass said: "I don't feel I'm coming here amid crisis."
He told the BBC: "We have had an electoral event. We have seen democracy at work and the question is how to move the diplomatic and political process forward."
Speaking before his meeting with Mr Haass, the SDLP leader, Mr Mark Durkan, said: "The two governments must show that the DUP has no veto by pressing ahead on all their commitments under the agreement. That means progress on equality, human rights and criminal justice. In particular, it means progress on demilitarisation.
"Tony Blair has admitted that there is no sense that the security situation is deteriorating," Mr Durkan added, "so why not close down further military towers and bases - and pass the sites over for social and economic use?
"There is no security need for so many of them. What better way to prove that the DUP has no veto than by taking them down?"
Looking ahead to the review, Mr Durkan added: "The lessons of the last five years must be learnt. The UUP demanded decommissioning as a precondition. Sinn Féin denied that decommissioning was a requirement. The result?
"Five years in which time and trust was lost, five years of bickering that only fed the DUP's vote. We cannot let the same happen in this review. We need to build a strong and determined pro-agreement axis that will protect the agreement from those who would tear it apart.
"We all need to make clear that the agreement will not be renegotiated."
Sinn Féin's Mr Martin McGuinness said last night in advance of a debate in Trinity College Dublin: "In last week's election, almost half a million people voted for pro-agreement parties. That is 70 per cent of the total electorate. Their voice must be heard and not drowned out by the rejectionist camp who gained around 30 per cent of the votes."
Returning to calls made by his party and the SDLP after their meeting on Tuesday, he added: "It is my belief that a way can be found through the current difficulties, but I am a realist.
"We have since the election sought meetings with the Taoiseach and the British Prime Minister and the other parties. We need to build a pro-agreement axis which will either compel the DUP into the institutions or, if they refuse, will leave them behind."