Foreign Affairs Minister Charlie Flanagan has promised to hold Northern Ireland's Secretary of State James Brokenshire "to account" after Sinn Féin objected to his chairmanship of talks aimed at restoring devolution at Stormont.
The spectre of direct rule from Westminster is looming large after a day of tension marked the reopening of negotiations between the DUP and Sinn Féin.
DUP leader Arlene Foster has told Gerry Adams's party that if it is concerned about her moves to enter a 'confidence and supply' arrangement with the UK Conservatives, it should help to quickly re-establish the Assembly.
She delivered a blunt message to Sinn Féin, warning: "If others decide that they are not coming back into the devolved administration here in Northern Ireland then those issues will have to be dealt with at Westminster," she said.
"It is really for Sinn Féin to decide where they want those powers to lie."
The Northern Ireland Executive has not sat since the election on March 2.
Mrs Foster's remarks came after Sinn Féin and other Stormont parties insisted Mr Brokenshire could not chair the efforts to restore power-sharing.
They are adamant the UK government can no longer cast itself as a neutral facilitator in the process, given Theresa May's intent to form a minority government with the DUP.
The dispute has prompted renewed calls for a chairman from outside the UK and Ireland to be appointed.
Mr Adams said: "Our resolve is to see these institutions put in place on the basis they were founded upon as quickly as possible.
"That could be done this time tomorrow morning or dinner time today. They are all rights issues subject to previous agreements.
"We made clear at the beginning of these talks that James Brokenshire is not an acceptable chair."
Likewise, SDLP leader Colum Eastwood said: "If James Brokenshire thinks for one second he can be an independent chair of these talks, he is absolutely wrong."
Last night, Mr Flanagan said the "heavy lifting" to reach a deal would have to be done by the parties.
He told RTÉ's 'Six One News' he will be "calling the parties to account" and "indeed to hold the Secretary of State to account to ensure there is no deviation from the Good Friday Agreement".
"I believe we can do it," he said.
A hard deadline of June 29 has been set for a deal to be struck, after which it is expected power will revert to London.