First Minister Peter Robinson has said he could not guarantee the future of the power-sharing government, but assured the DUP will not "walk away".
The leader of the DUP was speaking at the party's annual conference near Belfast on Saturday.
The DUP and Sinn Fein have been negotiating the transfer of policing and justice powers to Stormont.
The DUP said it needed to be satisfied community confidence existed before agreeing on the move.
Mr Robinson told the conference: "I fear no judgment from anyone faulting me for failing to act without the necessary measure of community support.
"Yet we may surely expect to be judged harshly if our terms are met and we were to decide for other reasons that the transfer of functions cannot proceed."
He called on Sinn Fein to show leadership and stop looking over its shoulder at the nationalist SDLP and dissident republicans over policing and justice.
"Threatening the institutions is destabilising. Threatening the DUP is just dumb," he added.
"I cannot guarantee the future of the Assembly but I can guarantee that it will not be the DUP that will walk away."
'Cave dwellers'
Mr Robinson said the vision of hardline unionist Jim Allister of politics free from Sinn Fein would be a step backwards.
The Traditional Unionist Voice took thousands of votes from the DUP in last summer's European elections.
"It was we in the DUP who secured devolution on terms acceptable to unionists and who finally scattered those birds of passage, the Direct Rule ministers, for so long the public face of a colonial system of government that consigned us all to the status of second-class citizens," Mr Robinson said.
The DUP leader also faces a threat from a combined Ulster Unionist and Conservative Party electoral ticket advocating closer ties with London.
Mr Robinson said: "And I warn those unionist cave dwellers who seek to wreck our achievements that they had better be prepared to come clean and explain to the people of Northern Ireland how on earth they think the return of Direct Rule, which is all they have to offer, represents a safer choice or a better way."
He said they did not want to leave to a future generation the toxic legacy that had been our inheritance.
"Short memories may now represent our most powerful challenge. I say to all those to whom my voice reaches: ignore the propaganda of our enemies; the DUP kept faith with its election promises...we took the tough decisions necessary."
He added: "The TUV's biggest lie is that there is an easier, better and attainable unionist alternative.
"And I will not remain silent while with smears, self-righteousness and sanctimonious arrogance they seek to direct unionism towards the fast-flowing rapids."
Reacting to Mr Robinson's speech, Mr Allister accused the DUP of panic.
"Mr Robinson is presiding over the most miserable and failed government anywhere in Europe and if this is the "success" he intends to build upon, then he engenders no fear in TUV.
"Neither the fury nor panic of the DUP conference will deflect us from seeking for Northern Ireland the durable and democratic devolution which it deserves, rather than the current shambolic failure which the DUP/Sinn Fein coalition has inflicted on us at Stormont."
© Press Association