Pressure was mounting on Peter Robinson after another Northern Ireland politician called on him to go.
Former First Minister in the Northern Ireland Assembly Lord Trimble claimed he had lost his authority following the exposure of his wife Iris’s affair with a lover.
However, DUP Finance Minister Sammy Wilson insisted he still commanded support.
Resignation by Mr Robinson could trigger an early Assembly election, Northern Ireland Secretary Shaun Woodward warned. Mrs Robinson is expected to step down within days.
Lord Trimble claimed: “To sit as leader in a party where the party summarily expels his wife without giving her any hint of due process or a soft landing is someone without authority in his own organisation.”
He said he expected Mr Robinson to step down within the next few days.
But Mr Wilson disagreed.
“As far as I am concerned he has got support, the stories about Iris don’t impugn him,” he said as he went to church in north Belfast, where Mr Robinson also attends.
If he falls, the post of First Minister and Deputy First Minister, held by Sinn Féin’s Martin McGuinness, would have to be filled.
Sinn Féin could delay nominating unless the DUP agreed to a timescale for the devolution of policing and justice from London to Belfast.
If this was not resolved within seven days it would fall to Mr Woodward to call an election.
He told the Sunday Times: “In those circumstances the Secretary of State is bound by legislation to set a date for election.”
Mr Robinson has vowed to clear his name after vehemently denying any knowledge of his wife’s irregular financial affairs, which if he did know should have been reported to the parliamentary authorities.
Mr Woodward refused to speculate about Mr Robinson’s future, but insisted the devolution process was “bigger than one man”.
Mrs Robinson’s membership of the DUP has been terminated and she is expected to leave Westminster, Stormont and Castlereagh Borough Council as early as next week.
Mrs Robinson announced over Christmas that she was quitting politics because of severe depression.
But she and her husband have since been plunged into crisis after it emerged that Mrs Robinson had secured £50,000 from two wealthy developers to help her 19-year-old lover Kirk McCambley set up a restaurant business in south Belfast.
Sinn Fein President Gerry Adams said they were focusing on ensuring the political institutions worked.
“The failure of the DUP to fulfil its political commitments and work the political institutions, as it agreed, on the basis of partnership and equality, has led to a considerable lack of public confidence in the political institutions,” he said.
PA