The British and Irish governments will take the decisions on Northern Ireland if NI politicians do not share power, the Irish foreign minister has said.
Dermot Ahern said the two governments will make decisions
Speaking on BBC Radio Ulster's Inside Politics programme Dermot Ahern said London and Dublin would adopt "an intergovernmental approach".
DUP MP Jeffrey Donaldson said any such move would be "completely unrealistic".
"It's time Dublin stopped being the bully boy and worked with the rest of us," he said.
"You can't bully unionists into accepting something that they find unacceptable at the moment and the sooner Mr Ahern realises that, the sooner we can make progress with the Irish government."
Mr Ahern had said joint authority was "probably not the preferred option".
"We would far rather people from Northern Ireland have their hand on the tiller of power," he said.
"But if they decide not to want that, then the two governments would have to step in and take decisions and people from Northern Ireland, their representatives, wouldn't really have any great say in that respect, and that's unfortunate."
He made his remarks as Tony Blair and Bertie Ahern prepare to unveil their take it or leave it blueprint for the political parties.
BBC Northern Ireland political correspondent Martina Purdy said the Irish foreign minister suggested the stalemate could not go on indefinitely and the governments would step in with another plan if the blueprint failed.
"The aim of the blueprint is to restore the assembly, but with the DUP and Sinn Fein at loggerheads about how it should operate, its success is far from assured," she said.
The British and Irish prime ministers are to give an assessment of the political process in Northern Ireland in about three weeks time.
Taoiseach Bertie Ahern said he and his British counterpart, Tony Blair, would make a joint statement on the talks.
He was speaking after a meeting with US President George Bush at the White House on St Patrick's Day.