Assembly parties have poured scorn on DUP plans for a "take it or leave it" budget designed to bring Stormont's financial crisis to a head.
DUP Finance Minister Arlene Foster's plans - most likely to be presented to the next Executive meeting a week from today - are set to overshoot the current budget by £600m in the hope that implementation of welfare reform will be agreed.
First Minister Peter Robinson believes the move will mean either Sinn Fein and the SDLP, who oppose the benefit changes, will have to change tack, or Westminster will have to wrest control of the welfare system.
His party's deputy leader Nigel Dodds yesterday raised the gathering crisis directly with Prime Minister David Cameron, who urged the five Executive parties to implement the Stormont House Agreement (SHA) they hammered out last December.
In the first Prime Minister's Question Time of the new parliament, Mr Cameron said the Executive needed to have a deliverable budget and everyone party to the agreement should implement it in full.
But Mr Dodds argued a sustainable budget was "impossible if Sinn Fein and the SDLP continue to ignore the financial realities of the position they have taken".
He said if Sinn Fein and the SDLP "are not prepared to act responsibly" then the Prime Minister and Government must take steps to preserve the integrity of the SHA by taking control of welfare.
But Sinn Fein's Conor Murphy insisted: "It is rich for David Cameron to call on the political parties to implement the Stormont House Agreement when his Government shifted the goalposts enormously by announcing plans for £25bn in further public spending cuts.
"These cuts were not part of any agreement."
Meanwhile, Alliance leader David Ford voiced doubt that the DUP plan was a "real option" and said other parties had not been willing to begin an intensive series of talks.
Mr Ford argued: "The DUP's plans for a budget based on the assumption of welfare being agreed has been described as being a phantom budget (which) reflects the difficulty in getting people to believe that it is a real option.
"It is beyond doubt that the clear way to resolve this impasse is by implementing the Stormont House Agreement and then agreeing a responsible budget, but the commitment of the other parties to achieving this is uncertain.
"In December last year I said that the Stormont House Agreement was a deal to do a deal. Sadly, five months on, some people still aren't prepared to make that deal."
Senior SDLP negotiator Alex Attwood said: "The DUP tabling a budget is a self-serving attempt to squeeze parties here and pressure London both on DUP terms. It does not change the character of what needs to be done.
"On 8th July with the Chancellor's emergency budget we will find out what in-year cuts mean and the scale and speed of the cuts to welfare to come.
"Any party that forces a Belfast budget on 8th June without reference to the London budget on 8th July ill-serves the full needs of our people."
Mr Murphy said there had been "very, very little detail" on the DUP's proposal, but his party was prepared to consider any options.
"The weakness in it is it doesn't seem to take account for the fact that, should we even agree a budget - a fantasy budget or a real budget - in the next number of weeks, that could be further undermined by further in-year cuts imposed by the Treasury."