Sinn Féin will table a proposal in the Stormont Assembly tomorrow afternoon calling for Arlene Foster to stand aside as Northern Ireland’s First Minister.
The proposal will call for Ms Foster to step back in order to facilitate an independent investigation into the so-called ‘cash for ash’ scheme.
The scandal revolves around the Renewable Heating Incentive (RHI) scheme which was designed to encourage businesses to replace older heating sources with more eco-friendly alternatives.
Errors in the scheme meant that the subsidies exceeded the cost price of the fuel - with businesses paid around £1.60 for every £1 of fuel purchased through the scheme.
As a result of the errors, the more fuel users burned, the more money they could claim - leaving the scheme drastically oversubscribed.
The Northern Irish Executive could now be facing a situation where they will end up paying out up to £400m (€477m) over the next 20 years as a result of the scheme - which was established in the North while Ms Foster was Minister of Department Enterprise, Trade and Industry.
The SDLP are also planning to put forward a motion of no confidence in Ms Foster.
In a statement this evening, Deputy First Minister Martin McGuinness said the RHI crisis was, “not about party politics.”
“It is not an orange or green issue,” he said. “It is about restoring the credibility of the power-sharing institutions and dealing with incompetence and allegations of corruption and abuse.”
"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.
Mr McGuinness called on Ms Foster to stand aside and insisted a statement the First Minister plans to make to the house tomorrow does not have his “authority or approval as deputy First Minister.”
“If she speaks, this will be in a personal capacity and not in her role as First Minister,” he said.
“There is no credibility in an inquiry established solely by the DUP or in the selective release of some documents by DUP departments.”
He called on all parties and assembly members to support the proposal for Ms Foster to stand aside.
Northern Ireland First Minister Arlene Foster. Image: Niall Carson PA Wire/PA Images
A spokesperson for the DUP said the party supports the need for an independent investigation, “free from partisan political interference, to establish the facts around the RHI scheme.”
“We are of the view that the conclusions of any investigation must be made public and that any investigation must be conducted speedily to assist in the process of building public confidence,” he said.
“We have been working to reach agreement with officials and others on the precise details of such an investigation over the last number of days."
The crisis over the RHI scheme reached new heights following a BBC interview with former DUP minster Jonathan Bell in which he claimed Ms Foster had ordered him to keep the scheme open despite warnings from the UK treasury regarding the potential loss to the taxpayer.
File photo dated 02/07/14 of Senior Democratic Unionist Jonathan Bell who has been suspended from the party. Image: Brian Lawless PA Wire/PA Images
Mr Bell also claimed there had been attempts to remove Ms Foster’s name from documents related to the scheme.
The DUP has rejected Mr Bell's claims and following a meeting of party executives over the weekend he was suspended from the party.
During the BBC interview he predicted his claims could put an end to his political career and called for a judge-led public inquiry into the affair.
David McNarry, the UKIP leader in Northern Ireland says Ms Foster is now ''fighting for her political life'' and warned that one of the two DUP representatives will not survive politically.
“It is one or the other,” he said. “If Jonathan Bell survives politically then Arlene Foster hasn’t and if Arlen Foster survives politically then Jonathan Bell is on his way out.”
Mr McNarry said Ms Foster will now have to convince the people of Northern Ireland that the RHI scheme has not wasted as much money as has been reported.