Sinn Fein have withdrawn from the talks process aimed at restoring devolution in Northern Ireland.
The republican party will not be nominating a deputy first minister to restore power-sharing on Monday, leader at Stormont Michelle O’Neill said, triggering another crisis at Stormont.
The current round of negotiations has run its course, she said.
“Today we have come to the end of the road.”
However the party’s president Gerry Adams said he believed the conditions to go back into devolved government would be achieved in the future.
Monday is the deadline for nominating a first and deputy first minister at Stormont or else Northern Ireland Secretary James Brokenshire is obliged to intervene.
Fresh elections or direct rule from Westminster could be imposed within a reasonable period.
Mrs O’Neill added: “The talks process has run its course and Sinn Fein will not be nominating for the position of speaker or for the executive office tomorrow.”
Power-sharing collapsed in January after a row over a botched green energy scheme predicted to cost the taxpayer up to half a billion pounds.
Sinn Fein has said it will not share power with the Democratic Unionists’ leader Arlene Foster as first minister until a public inquiry into the renewable heat incentive (RHI) is concluded.
Republicans have been seeking movement on issues like an Irish language act giving the tongue official status in Northern Ireland, a hugely symbolic measure but deeply problematic for some unionists.
They also want to see progress on legacy funding for Northern Ireland conflict victims waiting up to 45 years for answers over how their loved ones died.
Unionists want to see greater transparency from the Irish Government over Troubles killings.
The DUP has said Sinn Fein cannot dictate who it will nominate as first minister and Mrs Foster has refused to forgo the key role.
The five main parties only had until 4pm on Monday to resolve their differences or face another snap election.
Mr Adams said thinking unionism was at a crossroads and the DUP needed to represent everyone’s interests.
“We don’t have the basis for doing that, we are not going back to the status quo, but will we be back, will we get the institutions in place? Yes.”
A voting surge by Sinn Fein in the last Assembly election earlier this month saw the party come within one seat of becoming the biggest party at Stormont behind the DUP.
Public funding for services like health and education is in the balance without a deal to restore the administration.
Mr Brokenshire spoke to Prime Minister Theresa May on Sunday afternoon and said creating a functioning ministerial executive was a priority.
“This is the necessary first step to addressing the issues of greatest public concern, health, education and other public services in Northern Ireland.
“Even at this stage I urge political parties to agree to work to form an Executive and provide people here with the strong and stable devolved government that they want.”