Robinson, who earlier received the backing of his Democratic Unionist Party (DUP) to stay on as its leader, asked party colleague Arlene Foster to stand in as head of the province’s executive for a “short time”.
Robinson’s wife Iris said last week she had tried to kill herself last year after the extramarital affair. The subsequent financial disclosures have threatened the province’s already shaky power-sharing system.
Foster, the minister for enterprise, trade and investment, can deputise for up to six weeks under the rules of the provincial government, which is close to breaking point because of a dispute over when policing and justice powers should be moved from London to Belfast.
Foster, who defected to the DUP from the Ulster Unionist Party weeks after being first elected to the Northern Ireland Assembly in 2003, told the assembly she was sure that Robinson was going to clear his name.
“Me standing here is very much for a temporary period of time but I do so in the knowledge that when Peter comes back, that he will come back with a clear record,” she told deputies.
Robinson, who last week agreed to hold an investigation into whether he broke any regulations following the disclosures, maintained he had acted ethically and said he would continue to work on the outstanding policing issues.
Calls for the pro-British leader to step down grew in volume on Sunday when the former head of the province’s executive, David Trimble, said he expected his resignation within days.
A BBC television programme had asked why Robinson did not tell authorities that his wife, also a member of parliament, had failed to register 50,000 pounds ($80,000) received from two people and used to help a man with whom she was having an affair open a cafe in Belfast.
Robinson added that his wife, who has said she would leave parliament this week, was receiving “acute” psychiatric care.
