Talks to strike a new political deal in Northern Ireland will end tomorrow, with or without agreement, the Government has insisted.
Northern Ireland Secretary Theresa Villiers issued the blunt warning ahead of the resumption of long-running negotiations between her, the Irish Government and the five Executive parties at Stormont.
"It's 'make your mind up' time for Northern Ireland's political leaders," she said.
"These talks finish tomorrow, even if it takes all night. It there's no agreement tomorrow, there isn't going to be one, and the process ends in failure."
Over the weekend, Prime Minister David Cameron has been examining a financial proposal from the parties that could settle budgetary problems facing the power-sharing administration, particularly the impasse over non-implementation of welfare reforms.
The Government is set to respond tomorrow to their request for £2 billion-plus of extra funding and loan access over the next decade.
The plan essentially addresses long-standing nationalist concerns over introducing the Government's welfare policies in Northern Ireland by establishing a significant "cushion" fund, drawn from the Executive's budget, to support those hardest-hit by the changes to the benefits system.
But, while the region's politicians have agreed a potential way forward on finances, consensus is still proving elusive on other destabilising wrangles on the talks' agenda, such as those on flags, parades, the legacy of the past and the structures of Stormont.
Ms Villiers will again chair negotiations when they resume at Stormont House.
Another time factor is Chancellor George Osborne's pledge to devolve the long-sought power to set corporation tax rates to the Executive - but only if Stormont's financial issues are sorted out.
Mr Osborne said the Government would introduce legislation to implement the transfer of powers in this parliament. But for that time-frame to be achieved, the Government would need to start the legislative passage through Westminster as soon as possible.
While most of the issues on the agenda of the talks have been rumbling on for years without resolution, the row over welfare reform poses a pressing threat to the very future of the power-sharing institutions.
Failure to implement the policies would see the Executive hit with around £200 million of Treasury penalties - a financial burden that would likely bring down the administration.
It is understood the proposed package put to Mr Cameron by the five parties envisages penalties for delayed implementation of welfare reform being waived; increased borrowing powers to fund a civil service voluntary redundancy scheme; and a multimillion-pound Government contribution to fund new mechanisms to investigate the legacy of the Troubles.
Mr Cameron and Stormont's First Minister Peter Robinson and Deputy First Minister Martin McGuinness engaged in a conference call yesterday to discuss the proposals in detail.