Rishi Sunak has piled pressure on the Democratic Unionist Party (DUP) to get Northern Ireland's institutions up and running or risk harming the union.
The Prime Minister used a speech to mark the 25th anniversary of the Good Friday Agreement to praise political leaders for having courage "more powerful than a thousand bombs and bullets" to reach the landmark peace deal.
He said people on all sides "showed courage, imagination, and perseverance" to negotiate the agreement in 1998 which brought an end to decades of bloody conflict.
Addressing an audience in Belfast including ex-US President Bill Clinton, Mr Sunak said: "Let us glorify moderation, romanticise respect and make heroes of those with the courage to reject absolutes."
He turned up the heat on the DUP who have been resisting a return to powersharing since last year.
Mr Sunak said the fact that Stormont institutions have been non-functioning for nine of the last 25 years "should be a source of profound concern".
He said: "Over the long term that will not bolster the cause of unionism – I believe that deeply.
"So we need to get the institutions up and running – and keep them up and running."
He added: "History reminds us that nothing in Northern Ireland has ever been achieved by trying to get around one community or another.
"So any conversation about reform can only begin once the institutions are up and running again."
Mr Clinton, who was heavily involved in the Good Friday Agreement, also said it was time to "get this show on the road". by restoring powersharing.
He said the roadblock Brexit had posed for Northern Ireland's political and economic future had been "dramatically mitigated".
"The agreement was never supposed to be used to make sure there could be no self-government," he said.
"We know what the votes were at the last election, we can add them up, the allocation of seats in the parliamentary body, and it is time to get this show on the road."
The former President delighted locals by hitting the pub in Derry on Wednesday with SDLP leader Colum Eastwood, where he was pictured enjoying a pint of Guinness.
Political leaders descended on Northern Ireland to mark the anniversary of the peace deal, including ex-PM Sir Tony Blair, former Irish premier Bertie Ahern and European Commission vice president Maros Sefcovic.
Mr Sunak is expected to attend a gala dinner this evening alongside his predecessors Boris Johnson and Liz Truss, in what could make for an awkward encounter between political rivals.
