There is little to celebrate 20 years on from the Good Friday Agreement, the Ulster Unionist leader Robin Swann said.
Devolved Government at Stormont has not sat for 14 months in a dispute between former coalition partners the Democratic Unionists and Sinn Fein over protection for the Irish language and addressing the toxic legacy of Northern Ireland's violent past.
Mr Swann championed renewed reconciliation, tolerance, partnership, respect and mutual trust ahead of next week's anniversary of the landmark peace accord.
He said: "Sadly, the Belfast Agreement was not allowed to evolve and grow with society in the way it was envisaged because there were those who had much to fear from the normalisation of politics here.
"Twenty years on from 1998 there is little to celebrate when the DUP and Sinn Fein haven't been able to form a Government in the last 14 months, with one of them putting down a seemingly immovable red line of an Irish Language Act."
The ministerial Executive at Stormont collapsed when former Sinn Fein Deputy First Minister Martin McGuinness resigned in a dispute over the DUP's handling of a botched green energy scheme.
Endless rounds of negotiations led by the British and Irish Governments have failed to produce a breakthrough.
Mr Swann told his party's spring conference in Newcastle, Co Down, the absence of Government was hurting public services and unelected civil servants were making important decisions.
He urged an end to the "inhumane" treatment that survivors and victims of historical institutional abuse have suffered awaiting compensation payments recommended shortly before powersharing collapsed.
"We are a devolutionist party; we believe that the best delivery for the people of Northern Ireland is by the direction of locally elected Northern Ireland politicians.
"When the Assembly started to unravel, our party chairman, Lord Empey, warned others of how easy it was to walk down the steps, but not to underestimate how difficult it would be to get back up them.
"The current political impasse serves no one."