The British Prime Minister, Mr Tony Blair, launched a sharp attack on the Democratic Unionist Party yesterday, as fresh divisions in the Ulster Unionist Party spelt a renewed challenge to leader Mr David Trimble.
At Westminster, Mr Jeffrey Donaldson and colleagues the Rev Martin Smyth and Mr David Burnside rejected the UUP leadership's terms for their resumption of the party whip.
At the same time a leading pro-agreement unionist source in Belfast said Mr Trimble would be obliged to put any new deal with Sinn Féin to a meeting of the ruling Ulster Unionist Council (UUC) ahead of an election.
The Stormont source also predicted that Mr Trimble could face a legal challenge over any attempt to remove Mr Donaldson and Mr Burnside from the list of approved UUP candidates for the Assembly should they refuse to endorse the leadership's election manifesto.
Meanwhile Mr Blair's dismissal of DUP claims that it could force a renegotiation of the Belfast Agreement came amid renewed speculation by well-placed London sources that the threshold for cross-community voting in the Assembly might be lowered to counter any anti-agreement majority unionist bloc emerging from the election.
The Ulster Unionists and Sinn Féin have told The Irish Times this has not been an issue raised during their negotiation about an "acts of completion" deal.
However, two other informed sources close to the process have acknowledged that it could become an issue for the scheduled review of the agreement, should Mr Trimble fail to win the necessary votes to reinstate the power-sharing Executive following an election.
Mr Trimble's internal critics are predicting that they, together with the DUP, will have something like a 33/23 margin of advantage over Mr Trimble in the new Assembly.
And in the Commons yesterday, North Belfast MP Mr Nigel Dodds taunted Mr Blair, telling him that the Ulster Unionists and Sinn Féin could not deliver stability in Northern Ireland.
Demanding that there be "no more attempts to save Dave or to appease the IRA", Mr Dodds challenged Mr Blair to set the election date so that "the people of Northern Ireland will have their say and choose who will negotiate for them a better way forward based on an agreement which unionists as well as nationalists can support".
In reply Mr Blair laid bare his hostility to the DUP, telling Mr Dodds: "You say there is some other agreement out there waiting to be negotiated. As I said to some of your colleagues when they came to see me - I don't know what that agreement is but I do not see you or your colleagues negotiating a better agreement."
He said the agreement was "the only agreement that is on offer", and anything else would mislead the people of Northern Ireland.
The toughness of Mr Blair's assertion pointed up a key issue in the Sinn Féin/Ulster Unionist dialogue - how to ensure the "sustainability" of the institutions of government following an election which Mr Trimble will almost certainly be required to fight on two fronts.
Despite the predictions emanating from pro-agreement sources previously loyal to Mr Trimble, Mr Donaldson and other leading dissidents expect Mr Trimble to put any new deal to the UUC but seem disinclined to force a showdown in the teeth of an election if Mr Trimble chooses not to do so.
Against that - and while allowing they might yet be surprised by the terms of any IRA offer - Mr Donaldson and Mr Burnside are currently expecting to fight the Assembly election as Ulster Unionist candidates in opposition to their leader's policy.
This again raises the possibility that Mr Trimble, as his party's nominating officer, could refuse to endorse the dissident MPs as official UUP candidates, forcing them to stand as independents.
However, the Stormont source insisted this threat was based on a misreading of the legislation, which he maintained allowed "no discretion" to the nominating officer were candidates had been lawfully and properly selected by their constituency associations.