Peter Robinson will today warn Sinn Fein against threats to collapse the Assembly over the failure to agree policing and justice powers — but give the guarantee: “My party will not be walking away.”

The DUP leader is also set to disappoint republicans, and both the British and Irish governments, who are hoping his party conference speech this afternoon will signal some timetable for the handover of powers over police, prisons courts - or at least a date for a date. Instead the First Minister will spell out that progress is being made - but more work remains to be done and he will not be held to any deadline.

Mr Robinson will also launch a blistering attack on former colleague Jim Allister and his hardline Traditional Unionist Party.

Mr Robinson will warn dark mutterings from republicans in recent weeks over an emergent political crisis and threat to the future of the Assembly — with Deputy First Minister Martin McGuinness warning of “deep trouble” if agreement is not reached by Christmas — are clear evidence that Sinn Fein is under pressure rather than the DUP.

In such circumstances it would be “madness”, however, for the party to provide Sinn Fein with an exit strategy, he is to argue — and point out that while he cannot guarantee the future of the Stormont institutions it would not be the DUP who will walk away.

The prize of policing was the “fig leaf” Sinn Fein used to hide its embarrassment over compliance with the acceptance of the rule of law as part of the price it had to pay for getting into government, the East Belfast MP will argue.

After last week's controversy over the retention of the full-time reserve, which the party views as an important part of assessing whether sufficient confidence exists in the unionist community to allow the transfer of powers to go ahead — where he appeared to conflict with former Junior Minister Jeffrey Donaldson — Mr Robinson will also warn Prime Minister Gordon Brown of “inevitable consequences” if the party's advice is ignored.

With Mr Brown expected to become involved in renewed discussions with both Mr Robinson and Mr McGuinness next week, the DUP leader is to concede the party would be judged harshly if its terms are met and it still decides not to proceed with the new powers.

He will tell party activists that completing devolution is the unfinished business of unionism and if the conditions are right, it will be done — “on DUP terms”.

By contrast he is to characterise Mr Allister as “deserting the battlefield” and insist “Jim could do so much better — but chooses not to.”