A political crisis engulfing Stormont has left Northern Ireland facing a brutal election and a return to Westminster direct rule, Arlene Foster has warned.
The Democratic Unionist leader, who was forcibly removed as First Minister by her counterpart Martin McGuinness's resignation on Monday, also announced plans for a public inquiry into the renewable heating scandal at the heart of the Executive's collapse.
Mrs Foster said she would be willing to enter talks with Sinn Fein to avert an election, but the republican party made clear the region was heading to the polls.
Her pledge came as party colleague Gavin Robinson told MPs the downing of the Stormont Executive would halt the implementation of planned mitigation measures to support welfare claimants in Northern Ireland losing out under the UK Government's so-called "bedroom tax".
Sinn Fein president Gerry Adams said the situation was of the DUP's making.
He insisted the Renewable Heat Incentive (RHI) furore was only one of many issues his party needed to be resolved before re-entering government with the DUP.
The republicans want the DUP to give ground in relation to issues such as the Irish language and the ongoing ban on same-sex marriage.
Mrs Foster, in turn, said her party wanted to review the fundamental structures of Stormont's mandatory coalition arrangements, with a view to moving to voluntary coalition government.
With that number of seemingly intractable disputes to overcome, even if the DUP and Sinn Fein were returned as the two largest parties following a snap poll, the prospect of them agreeing to form an executive are slim.
That raises the spectre of the UK Government suspending the institutions and reintroducing direct rule after 10 years of unbroken devolution.
"I have no doubt that if the election proceeds it will be a brutal election, it will be a very difficult election," said Mrs Foster.
"Undoubtedly we are in for a period of direct rule.
"I really do regret that. I think what the people of Northern Ireland want is stability but that has all been thrown into very sharp relief yesterday by the actions of Sinn Fein for hugely party political reasons and not for any other reason."
Accusing the DUP of not honouring the principles of powersharing, Mr Adams said his party was now preparing for an election and would only resume a partnership with its unionist rivals on the basis of "equality and fairness".
"People need to come out in the election if they are for accountability, for transparency, if they are against corruption, for equality and fairness," he said.
"We have come a long distance and have a good way to go yet.
"Sinn Fein is totally wedded and bedded in this process so we want to go back with a mandate which allows us to engage with whoever wants to be in the Executive, but as Martin (McGuinness) pointed out, there will be no return to the status quo."
The departure of Mr McGuinness as Deputy First Minister amid a row over the RHI forced Mrs Foster from her job as First Minister as well. The structure of their political office means one cannot be in post without the other.
Theoretically the parties have seven days to resolve their differences before Northern Ireland Secretary James Brokenshire has to call an Assembly election.
The prospect of such an eleventh hour deal is slim.
Earlier, Mr Brokenshire appealed to the leaders to step back from the brink.
He told the Commons the situation at Stormont following Mr McGuinness's resignation was "grave" and expressed concern about the consequences of an election.
He urged the parties to work together to find a resolution and safeguard the progress made under the peace process.
"We do have to be realistic - the clock is ticking," he added.
"If there is no resolution, an election is inevitable despite the widely held view that this election may deepen divisions and threaten the continuity of the devolved institutions."
Mrs Foster insisted an inquiry into the RHI, under the terms of the 2005 Inquiries Act, could go ahead without the sign-off of Sinn Fein.
"This is vitally important from a political perspective but also fundamental for me on a personal basis," she said.
"I have been quite disgracefully maligned in the most vicious manner and therefore it is of the utmost importance that the truth comes out."
Mr McGuinness's decision to walk away after 10 years of sharing power with the DUP came in response to Mrs Foster's refusal to stand aside to facilitate a probe into the ill-fated RHI - the so-called "cash for ash" scandal.
The doomed energy scheme has left the administration in Belfast facing a £490 million bill.
The DUP leader oversaw the RHI during her time as economy minister.
She had repeatedly rejected Sinn Fein's demands to step down temporarily pending the outcome of a preliminary investigation.
The state-funded RHI was supposed to offer a proportion of the cost businesses had to pay to run eco-friendly boilers, but the subsidy tariffs were set too high and without a cap, so it ended up paying out significantly more than the price of fuel.
This enabled applicants to "burn to earn" - getting free heat and making a profit as they did so.
Claims of widespread abuse include a farmer allegedly set to pocket around £1 million in the next two decades for heating an empty shed.
Sinn Fein Finance Minister Mairtin O Muilleoir said Mrs Foster's inquiry plan was not credible.
"It would be a laughing stock if we now had an inquiry that was set up at her behest," he said.