The North's Minister of Enterprise, Trade and Investment, Sir Reg Empey, has confirmed that Mr David Trimble has designated him to exercise the functions of First Minister following his own resignation from the post.
Sir Reg denied he was a "caretaker" First Minister, as the position and Mr Seamus Mallon's joint post of Deputy First Minister were no longer filled due to Mr Trimble's resignation yesterday over the lack of IRA decommissioning.
However, he confirmed to the BBC's Inside Politics programme on Saturday, hours before Mr Trimble's resignation, that he had been asked to take over the functions of the office. "It is possible for Mr Trimble to appoint someone, a minister, to carry out some functions of the office, but there is no provision for any Deputy or acting First Minister."
He said it was "only a sticking plaster solution for a very short time" and he hoped to see the UUP leader back as First Minister in the future.
The nomination enables Executive and North-South ministerial meetings to be called, and for Mr Mallon to continue exercising power for six weeks before the necessary joint reelection.
"We cannot leave the government of Northern Ireland in the hands of nationalist ministers for a month-and-a-half. There could be emergencies, for example if we had a further outbreak of foot-and-mouth, and there are financial matters that need dealing with," Sir Reg said.
Sir Reg said Mr Trimble wants the institutions to continue functioning. The Sinn Fein chairman, Mr Mitchel McLaughlin, said his party regretted Mr Trimble's resignation, which he said had created a crisis in the process. "If he were really wedded to the Good Friday agreement he would not have resigned."
He said Mr Trimble had "chosen to collapse" the institutions over IRA weapons that had been silent for seven years.
Commenting on Sir Reg's appointment, the DUP Assembly Member for East Belfast, Mr Sammy Wilson, said only Sinn Fein's exclusion from the Executive offered a solution.
"Reg Empey may have the unenviable task of being the elastoplast to cover the wound which was caused by including IRA/Sinn Fein in government but a sticking plaster will not remedy the problem."