The Stormont powersharing institutions are “essential” for building the case for Northern Ireland’s place within the Union, Sir Jeffrey Donaldson has told the DUP conference.

The DUP leader also said a time is coming when his party must decide if ongoing negotiations with the Government are a basis for ending the trade border impasse caused by the Northern Ireland Protocol.

Addressing delegates in Belfast, Sir Jeffrey said the DUP had “a proven track-record of saying yes and leading from the front”.

However, he also warned he would not be afraid to say no if discussions did not result in a deal which adequately dealt with trading concerns.

The DUP withdrew first minister Paul Givan from the Stormont executive in February 2022 in protest against the internal UK trade barriers created by the post-Brexit protocol.

Powersharing is unable to function in Northern Ireland without the participation of the largest unionist party.

The UK and EU agreed the Windsor Framework earlier this year in an attempt to address unionist concerns about the protocol, but the DUP has indicated it will not return to the Stormont Assembly until the Government provides further assurances over Northern Ireland’s place in the UK internal market.

One of the main parts of the framework – the green/red lane system for the movement of goods – became operational at Northern Ireland ports earlier this month.

The DUP conference is taking place against the backdrop of the continued negotiations between the DUP and the Government.

Sir Jeffrey told delegates their conference is taking place “when all eyes are upon us”.

He said: “Not for the first time, London, other Northern Ireland political parties, and no doubt even those in Dublin, will be straining to hear what is said from our proceedings.”

Sir Jeffrey said the Government has to “undo the harm” caused by the Northern Ireland Protocol.

He said the Windsor Framework represented progress but “did not sufficiently deal with some of the fundamental problems at the heart of our current difficulties” over Brexit.

He said: “Upon careful reflection and consideration of the facts, and not the spin, we concluded that the framework did not meet our seven tests as set out in our 2022 assembly election manifesto.

“Our phased withdrawal from the Northern Ireland executive was designed to highlight to the UK Government and the EU that they needed to address unionist concerns about the protocol, which for too long had been ignored, and to spotlight the harm it was doing to Northern Ireland’s place in the Union.

“Our view on this has not changed.”

He added: “Despite the misguided analysis of some, and the prejudiced commentary from others who have always cheer-led for the original protocol, we have remained focused on our aims and objectives, determined to secure further progress at this time.”

He said the DUP alone had led in securing changes to the protocol, adding his party recognised the need for a pragmatic approach to dealing with the customs arrangements for the movement of goods entering the EU from Northern Ireland.

He told the conference: “Unionists rightly and reasonably recognised that were they to pursue the creation of a hard customs border between the United Kingdom and the Republic of Ireland, even though that is where the international border remains, such a demand would have struck at the heart of the delicate balances that comprise the Belfast Agreement.

“Yet the same is the case with imposing a border down the Irish Sea and disrupting our UK internal market for British goods.

“Let me again be clear to this conference, the imposition of a customs border on goods moving between Great Britain and Northern Ireland and remaining within the UK internal market was unnecessary and unacceptable in 2019; it was unnecessary and unacceptable in 2021 and it is unnecessary and unacceptable now.”

He said discussions with the UK Government over post-Brexit trading arrangements were making progress and added he was hopeful remaining concerns could be “addressed as quickly as possible”.

He added: “There will come a point when we have to determine if the outcome of the discussions measures up to our objectives and manifesto commitments, and whether there is a sustainable basis for moving forward.

“This party has a proven track-record of saying yes and leading from the front when it’s right to do so.

“Equally, we will not be afraid to say no if we conclude that what is on offer does not adequately deal with our fundamental concerns and is not in the best long-term interests of our place in the Union.

“This party will not be bullied or threatened by anyone, whomever they purport to represent. We will take our own counsel and our own decisions.”

He added: “If we want to make the positive case for the Union, then having local institutions that succeed in delivering for everyone in Northern Ireland is an essential element in building our case.

“We must not allow republicans to perpetuate the myth that Northern Ireland is a failed and ungovernable political entity and therefore, in their view, a divisive border poll is required.

“We can and must make Northern Ireland work for all its people.”

He added: “Our system of government is far from perfect and when it returns, we must collectively dedicate ourselves to ensuring – even when it is difficult – that decisions are taken that make a real difference to the lives of the people we represent.”