The Good Friday agreement was “based on compromise”, which should be the defining message for the next chapter in Northern Ireland, Rishi Sunak has said on the peace deal’s 25th anniversary. The prime minister said there was “work to be done” by a new generation of politicians to restore government at Stormont “as soon as possible”, as he and Ireland’s taoiseach, Leo Varadkar, prepare to intensify work to broker a way out of the deadlock. Sunak will meet the US president, Joe Biden, on Tuesday evening on a visit to mark the anniversary, though on a shorter trip than initially expected. Biden is due to address Ulster University’s newly opened Belfast campus on Wednesday and then travel to the Republic. The Sinn Féin leader, Mary Lou McDonald, expressed frustration on Saturday that Biden would have no opportunity to address Stormont because of the Democratic Unionist party’s refusal to enter power sharing, saying he should be received by the “first minister, Michelle O’Neill, and should be addressing the assembly”. Sunak said the Good Friday agreement was due to the partnership of the British and Irish governments as well as “huge international support from our closest allies”, as demonstrated by Biden’s visit. “But most importantly, it is based on compromise in Northern Ireland itself,” he said. “As we look forward, we will celebrate those who took difficult decisions, accepted compromise, and showed leadership – showing bravery, perseverance, and political imagination. “While it is time to reflect on the solid progress we have made together, we must also recommit to redoubling our efforts on the promise made in 1998 and the agreements that followed.” He said the promise of the Good Friday agreement was “economic opportunity, prosperity, and stability – it is a promise we must continue to fulfil. So we must get on with the business of governance. “We stand ready to work with our partners in the Irish government and the local parties to ensure that the institutions are up and running again as soon as possible.” The Labour leader, Keir Starmer, who spent several years advising the Police Service of Northern Ireland in the wake of the Belfast agreement, also said the commemorations would mark the achievements of politicians who had brokered the deal, including the last Labour government. “But we always recognise this achievement does not principally belong to us, but to the people of Northern Ireland who, over a quarter of a century, have overcome differences that once seemed insurmountable and shown they can work together to build a better future for themselves and for the generations to come,” he said. However, he said the country was now at “another crossroads” 25 years later, not only with the impasse at Stormont but with recent years of difficult Anglo-Irish relations during Brexit negotiations. “We must use the spirit and the trust built by the architects of the Good Friday agreement to push us forward to another 25 years of peace and prosperity,” he said. Ahead of the commemorations, Sunak has come under renewed pressure over post-Brexit plans to ditch thousands of EU laws by the end of this year. The Observer revealed on Sunday that the government has dropped plans to hold the report stage of the retained EU law bill in the Lords soon after Easter, after Tory peers warned they would join a mass cross-party revolt. On Sunday, the former secretary of state for Northern Ireland, Peter Hain, and the former British ambassador to the US, Sir Kim Darroch, said Sunak should drop the bill, as well as veiled threats to withdraw Britain from the European convention on human rights (ECHR), which is directly cited in the text of the Belfast agreement. Hain, who brokered the St Andrews agreement, which restored power-sharing in 2007, said: “Dogmatic adherence to Brexit ideology and nativism continues to threaten this delicate peace and it is essential that the government recognises the risks to the Good Friday agreement if they force the UK out of the ECHR or blindly scrap important legislation.” Darroch, who now chairs the anti-Brexit group Best for Britain, said the Good Friday agreement was “a model of diplomatic engagement, transformational for Northern Ireland, and a shining example of the benefits of internationalism. “The message it carries for today is that we need to continue to work constructively with others, to honour our international commitments, and to abandon ideas that would put these principles at risk, like the retained EU law bill.”