Sinn Féin has warned a collapse of the powersharing institutions at Stormont is an option if First Minister Arlene Foster refuses to stand down to allow a probe into her handling of a botched green energy scheme.
Democratic Unionist leader Mrs Foster has steadfastly rejected calls to step aside amid an "ash for cash" crisis that has engulfed the devolved administration in Belfast.
She faced down a motion of no confidence during a day of drama on Monday that included a mass walkout from the Assembly chamber.
But while the Christmas break is set to take some political focus off the Renewable Heat Incentive (RHI) furore, Sinn Féin has made clear the issue must be dealt with in the new year.
The RHI has landed Stormont with an overspend bill of an estimated £400m over 20 years.
It was supposed to offer a proportion of the cost businesses had to pay to run eco-friendly boilers, but it ended up paying significantly more than the price of fuel, enabling 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 £1m in the next two decades for heating an empty shed. Mrs Foster was the minister in charge of the scheme at its inception.
Now First Minister, she has the party strength in the Assembly to defeat any bid to censure her.
However, the structure of the DUP/Sinn Féin-led governing executive is predicated on the participation of both partners - so if Sinn Féin walks away the institutions would fall, with an election likely to follow six weeks later.
While members of the republican party have stressed their desire to reach a resolution, they have also warned that a walkout would be considered if Mrs Foster does not accede to their request to step down - without prejudice - while a judge-led probe is undertaken.
When asked if Sinn Féin Deputy First Minister Martin McGuinness would withdraw if Mrs Foster remains at her desk in January, his party colleague John O'Dowd said: "All options are on the table."
The MLA told BBC Radio Ulster: "The loss of public confidence in the political institutions may require that event to happen - that's the reality, that's the depth of the political crisis we are in."
Sinn Féin president Gerry Adams said: "This issue is not going away. The DUP should use the time over the Christmas period wisely and do the right thing."
His party will table a motion in the Assembly in January calling for: a public inquiry; steps to mitigate the overspend; and for Mrs Foster to step down temporarily while the investigation takes place.
Current DUP Economy Minister Simon Hamilton and Sinn Féin Finance Minister Mairtin O Muilleoir are working together on plans to claw back some of the finances committed.
In the Assembly on Monday, Mrs Foster described the RHI affair as her "deepest political regret", but insisted she was going nowhere.
"I remain as committed today as I did on the day I was elected as First Minister to fight the good fight, finish the race and keep the faith," she said.
The SDLP's motion of no confidence was supported by a majority of voting MLAs (39-36) but was defeated because it did not secure the required level of cross-community support, due to DUP opposition.
Ahead of the motion debate, all non-DUP members of the Assembly walked out of the chamber amid an acrimonious row over Mrs Foster's right to make a statement on the RHI, without the required approval of Mr McGuinness.
In extraordinary scenes, which saw Speaker Robin Newton face a barrage of critical questions, Mrs Foster made her statement to rows of empty benches with only her party colleagues for company.
The DUP leader then fielded questions from her MLAs in an otherwise empty chamber.
The scandal reached fever pitch last week when former DUP economy minister Jonathan Bell broke ranks to level a series of claims against his leader and party advisers.
In a TV interview, a tearful Mr Bell said God told him to come clean as he claimed a "highly agitated and angry" Mrs Foster demanded he keep the RHI open for an extra fortnight despite its huge losses.
Mrs Foster strongly rejected the claims.
Mr Bell was suspended by the party over the weekend.
On Monday, Mr Bell claimed he had an email containing critical information about the scandal. The email was subsequently made public by Mr Hamilton.
In it a senior civil servant highlighted there had been "some initial reluctance to make the necessary legislative changes" to limit payments.
However, the letter from Andrew McCormick, permanent secretary at the economy department, did not reveal the source of the reluctance.
Much of the scrutiny on Mrs Foster has focused on how she responded to concerns highlighted by a whistleblower during her time as economy minister.
There was a flurry of claims last week about whether the individual raised concerns directly to Mrs Foster, or if she only outlined them after Mrs Foster passed her on to meet departmental officials.
The DUP published an email from the whistleblower last week that made no mention of her RHI concerns - the party cited it to demand an apology from those who said she should have done more.
Another email has since emerged, sent directly to Mrs Foster in 2013, that did raise specific concerns about the scheme.
Mrs Foster has apologised to the whistleblower on behalf of her former department.
On the issue of what information was passed directly to her, she added: "Unfortunately, it has been difficult to establish the exact facts around contact between this concerned citizen and myself and the department."