The future of Stormont's political institutions is in jeopardy, Northern Ireland Secretary Theresa Villiers has said.
In a statement to the House of Commons, Ms Villiers said she was confident crunch talks focused on paramilitary activity and welfare reform could save the crisis hit devolved Assembly.
She said: "We strongly support the power-sharing devolved institutions established under the Belfast Agreement.
"The future of these institutions is in jeopardy if the two very serious matters I have outlined here today are not resolved.
"I do not under-estimate the challenges we face, but I believe that a way through can be found and that is what we will be striving to achieve as we embark on this new talks process with urgency, focus and determination."
The power-sharing Executive has been under threat of collapse since police said IRA members were involved in the murder of Kevin McGuigan in east Belfast last month.
Police believe Mr McGuigan was killed by individual members of the Provisional IRA in revenge for the death of prominent republican Gerard "Jock" Davison in May.
Although the Police Service of Northern Ireland (PSNI) Chief Constable George Hamilton has insisted the IRA is not back on a war footing, disclosure that the organisation still exists has rocked the political establishment.
On Monday, the Democratic Unionist Party (DUP) said there would be no further routine meetings of the Executive until the latest crisis was resolved.
If the latest round of crunch talks, expected to last for four to six weeks, are unsuccessful, First Minister and DUP leader Peter Robinson has warned he would pull his ministers out.
The Ulster Unionist Party withdrew its only Executive minister Danny Kennedy in August, claiming it could no longer trust republicans.
Ms Villiers will be joined at Stormont House by Irish Foreign Affairs Minister Charlie Flanagan.
If an institution similar to the Independent Monitoring Commission which assessed paramilitary ceasefires was restored it would ask different questions, Ms Villiers said.
"It is already unsustainable, there are already ministers who...cannot sign off on projects because of the uncertainty around the availability of funding to come."
She has received representations from the DUP, Northern Ireland's largest party, about suspension of the Assembly.
"The Government does not feel that the time would be right to suspend the institutions at this stage and under these circumstances.
"If the circumstances were to change in the future we would of course need to look at all our options."
Ms Villiers said officials would not be renegotiating last year's Stormont House Agreement, which addressed a number of issues left over from the Northern Ireland peace process.
"We are simply finding the way to remove the blockage of implementation and make sure the agreement is implemented in full."
She said the discussions would be similar to previous talks.
"Some have succeeded, some have not. Even if we have a successful outcome culminating in agreement, unfortunately that is just a step on the road of a much longer process to get implementation properly effected."
The Northern Ireland Secretary said the police assessment of the IRA may change over time.
"There was never a justification for politically motivated violence in Northern Ireland, from whichever side of the community it came.
"During the Troubles, paramilitary organisations inflicted huge suffering on thousands of ordinary people.
"These organisations should never have existed in the first place, they should not exist today and they should disband."
She said Northern Ireland risked losing out on the ability to reduce its business tax to encourage economic development unless a deal was struck.
"We are a One Nation Government and we want to build a Northern Ireland where politics works, the economy grows and society is stronger and more united."
She added the Government was committed to a fully functioning Assembly.
"It is hugely important that we support the devolved institutions.
"It would be such a step back to end up with direct rule (from Westminster)."