Ireland’s taoiseach has said it is unacceptable for one party in Northern Ireland to block others from taking power, as he visited Belfast to try to break the deadlock over the Brexit protocol and power-sharing at Stormont. After meetings with party leaders, Micheál Martin said the Northern Ireland assembly and executive should be formed while negotiations continued between the UK government and the EU over the protocol. “Our view is there should be parallel discussions,” he said as he urged the DUP to abandon its decision not to return to power-sharing until “decisive action” was taken over reforms to Northern Ireland’s Brexit arrangements. Earlier he said it was “unheard of in a democratic world” that a parliament could not convene after an election. “We can’t have a situation where one political party determines that the other political parties can’t convene in a parliament,” he said. He said he understood there were “legitimate issues” to be discussed with the DUP but that the only answer to the problem was collaboration, not confrontation. He accused Boris Johnson of “moving the goalposts” over the protocol and going “too far in a unilateral way” in the UK’s approach to Northern Ireland after the foreign secretary, Liz Truss, announced plans to introduce domestic laws to override the protocol if the EU did not meet the government’s demands. His visit came as the first minister elect, Sinn Féin’s Michelle O’Neill, flew to Scotland for talks with Nicola Sturgeon. They discussed the protocol and the deepening cost of living crisis. The Scottish first minister said unilateral action to disapply part of the protocol would have “incredibly damaging effects”, and “pitching us into a trade dispute with the EU could be what tips us over [into recession]”. O’Neill, who requested the meeting in Edinburgh, said she updated Sturgeon on the benefits of the special Brexit arrangements allowing Northern Ireland, uniquely in the UK, to continue free trade access to the EU and how this was “yielding benefits for business and our local economy”. Back in Belfast, Martin said UK claims that the EU was being intransigent and inflexible were exaggerated. “I spoke to Boris Johnson and I have to nail this, this idea that somehow the European Union is being inflexible on this is just not the truth, it doesn’t stack up. “What has happened now is a certain unilateralism on behalf of the British government saying ‘our way or no way’ and you don’t negotiate with the European Union on that basis, particularly when you have signed off on the agreement that you now don’t like.” His comments came as a US delegation of Republican and Democratic congressional representatives landed in Europe for a week of talks with Brussels, London and Dublin leaders to try to calm tensions over Northern Ireland. They will meet Truss on Saturday morning. Richard Neal, the chair of the US ways and means committee, said he would be reminding everyone that the 1998 peace agreement was hard won and not just a “cavalier achievement” that could be used for domestic political ends. His trip coincided with a broadside by the US House speaker, Nancy Pelosi, who said unilateral action on the protocol could damage the UK’s chances of a trade deal. The DUP leader, Sir Jeffrey Donaldson, told the BBC in response that if “Pelosi wants to see the agreement protected then she needs to recognise that it is the protocol that is harming and undermining the agreement and that is why we need to deal with it”. He said the protocol had “changed some of the key principles” of the accord and “made it impossible to have power-sharing on the basis of consensus”.