MARTIN McGuinness has said there is an overwhelming desire in the community for Arlene Foster to step aside amid a growing political crisis over a green energy scheme scandal.
In a New Year's Day message, the Deputy First Minister said the First Minister and her party needed to accept widespread demand for a thorough investigation into the Renewable Heat Incentive (RHI) scheme.
"There is also no doubt that we are facing a serious growing political crisis in the north as public confidence in the political institutions has been grievously undermined by the RHI debacle and the DUP's failure to deal responsibly and adequately with it," he said.
"In order to address these challenges, the DUP and its leader Arlene Foster need to accept there is an overwhelming desire in the community to deal with this issue and for Arlene Foster to step aside as first minister pending a preliminary report."
The Sinn Féin chief said Mrs Foster's stepping aside would allow for an investigation led by an independent judicial figure from outside Northern Ireland and appointed by the Attorney General.
"A rigorous process to recoup as much of the money as possible must also be put in place," he added.
"We need to restore public confidence in the credibility of the political institutions, ensuring they deliver for the people."
Mr McGuinness's repeated demand for his power-sharing partner in the executive to step aside follows the publication of a letter Mrs Foster sent to bankers about the RHI when she was economy minister in January 2013.
In it, she said payments made under the scheme would be "guaranteed".
Video: Arlene Foster speaking to the Irish News in October about RHI:
She also told the region's leading banks that the state-funded eco-subsidies, set up by her as economy minister, offered applicants a "good return on investment".
The revelations have raised further concern over her claim that half of the estimated £490 million public money overspend could be clawed back.
The scheme offered businesses subsidies to run eco-friendly boilers, but the tariffs were set too high and, unlike the same scheme in Britain, there was no cap.
This allowed applicants to "burn to earn" – getting free heat and making a profit as they did it.
Claims of widespread abuse include a farmer allegedly set to pocket around £1 million in the next two decades for heating an empty shed.
Economy minister Simon Hamilton has defended his party leader in recent days after a wave of calls for her to step aside.
He accused opposition MLAs attacking Mrs Foster of offering nothing more than "party political attacks and resignation calls".
But Ulster Unionist peer Lord Empey said Mrs Foster must take responsibility for the "biggest financial scandal since partition in 1921".
"Given the scale of this disaster and given Mrs Foster's involvement at all stages, I think any objective observer would conclude that she must step down and take responsibility," he said.
"That's how it works in the real world and in all walks of life - ask any premier division football manager.
"There is simply no escape from this fact."
Lord Empey said if the First Minister continues to resist calls to step aside she will drag the crisis out "until she damages herself and the (power-sharing) institutions perhaps beyond repair".
"I hope she reflects on these matters during the recess, takes the necessary action by resigning and allows Stormont to start 2017 with a determination to fix this mess, and go forward to deliver some much-needed effective action to raise living standards and resolve the problems in the health service which are blighting the lives of so many," he added.
