Sinn Fein has announced that it will bring a proposal to the Northern Ireland Assembly on Monday calling for Arlene Foster to stand aside as First Minister.
The party had earlier on Sunday refused to say whether it would back a similar motion planned by the SDLP.
But on Sunday evening a statement was released on behalf of Deputy First Minister Martin McGuinness saying his party plans to bring a proposal to the Assembly on Monday calling for the First Minister Arlene Foster to stand aside to facilitate an independent investigation into the RHI scandal.
"The current crisis is not about party politics," Mr McGuinness said.
“It is not an orange or green issue. It is about restoring the credibility of the power-sharing institutions and dealing with incompetence and allegations of corruption and abuse.
"That is my sole focus and the sole focus of Sinn Féin.
"It is my firm belief the only way to establish the truth of what has occurred and to begin to restore public faith in the institutions is for an independent, time-framed and robust investigation to take place.
"The First Minister should stand aside to allow this. There is also an urgent need to minimise the cost of the scheme to the public purse.
"Given the First Minister’s failure thus far to accept this Sinn Féin will bring forward a proposal to the Assembly which calls on the First Minister to stand aside until this independent investigation brings forward a preliminary report.
“We are calling on all parties and MLAs to support this."
Mr McGuinness went on to claim that a statement which Mrs Foster plans to make to the Assembly on Monday does not have his "approval".
“The statement which Arlene Foster plans to make to the Assembly tomorrow does not have my authority or approval as deputy First Minister," he said.
"We have told the DUP this.
“If she speaks this will be in a personal capacity and not in her role as First Minister.
“There is no credibility in an inquiry established solely by the DUP or in the selective release of some documents by DUP departments.
“If the DUP does take a unilateral approach, disregarding the authority and joint nature of the Executive Office on an issue which is cross-cutting, with massive budgetary implications and which is undermining public confidence in the political institutions this will have grave consequences."