Britain's Northern Ireland Secretary Brandon Lewis has urged DUP leader Jeffrey Donaldson to nominate a deputy first minister to allow the resumption of a fully functioning devolved government.
Mr Lewis was speaking hours after the conclusion of a Stormont election that saw a historic victory for Sinn Féin to become the largest party and win the entitlement to nominate a first minister.
Mr Donaldson has called for action on the Northern Ireland Protocol before re-entering the executive.
Mr Lewis is to meet the leaders of the Stormont parties tomorrow to talk about resurrecting the Assembly.
Sinn Féin has won 27 seats while the DUP has 25, the Alliance Party 17, the Ulster Unionists (UUP) nine and the SDLP eight, with four others elected.
Minister for Foreign Affairs Simon Coveney has said there is a need for partnership from Britain - not threats - to solve the Protocol issue.
Sinn Féin leader, Mary Lou McDonald, told RTÉ's This Week she does not accept "as a matter of conclusion" that an Executive will not be formed at Stormont.
"There has to be an Executive. I mean, all of us have heard - in the course of a very long campaign - the real stories of people struggling."
Everyone now needs to get back to work, she said, and "Michelle O'Neill will lead our team to the Assembly tomorrow".
Ms McDonald said the date of a border poll is a speculative exercise, but the process of planning for peaceful, orderly and democratic change must now begin.
She said none of the Protocol issues are beyond resolution and "Boris Johnson and his government need to start working proactively in good faith with the EU".
However, Mr Lewis said it is "widely acknowledged there are issues with the Protocol that need to be resolved".
He told the BBC's Sunday Politics programme that the full Protocol has not yet been implemented with a number of grace periods running on aspects of the post-Brexit treaty.
Unionists strongly oppose the Protocol as they say it places a border in the Irish Sea between Northern Ireland and Britain.
Mr Lewis restated his position that the UK government would like to reach agreement with the EU over resolving issues with the Protocol, but said nothing has been taken off the table.
He urged Mr Donaldson to nominate a deputy first minister to get a devolved government fully working again at Stormont.
The executive has been unable to fully function since February when the former first minister Paul Givan resigned as part of the DUP's call for action against the Protocol.
"It's for the UK government to do the negotiations, Jeffrey and the DUP and all parties in Stormont should [come] together and bring Stormont back to deliver on the domestic issues for Northern Ireland," he said.
Protocol issues must be resolved - Coveney
The Minister for Foreign Affairs said outstanding issues surrounding the Northern Ireland Protocol must be resolved in order to enable parties come together.
Speaking on RTÉ's This Week, Mr Coveney said the only way to achieve this is through partnership and intense negotiations.
The maximum flexibility must be applied to the existing agreement to ensure it is implemented in a pragmatic and sensible way, he said.
The minister said there is a responsibility now on everyone to assist the parties in Northern Ireland to come together.
Mr Coveney said: "I certainly hope that by doing that we can assist the parties in coming together because the last thing we need now in Northern Ireland is a collapse of the institutions and all the tension and polarisation that would flow from that.
"And there's a responsibility, I think on us all to respect how the people voted and to find a way of working with the parties to put an Executive and Assembly that can work back in place."
He said efforts must now be made to differentiate between goods coming into Northern Ireland that are not at risk of travelling on to the EU or south of the border and apply a different system to these goods.
He said the EU is willing to look at such a proposal but that the EU needs a partner in order to make it happen.
Minister Coveney said people have the right to aspire to a border poll, just as those who want to remain in the union have a legitimate right to that view.
He said the focus over the coming weeks and months must be on building trust between the parties in the North and removing obstacles so that a devolved government can function again.
US Gov calls on N Ireland's political leaders to re-establish a power-sharing executive, saying critical challenges concerning economy, health + education "best addressed through the collective efforts of a devolved government chosen by, and accountable to, its people." @rtenews pic.twitter.com/qeKJyVwFSr— Vincent Kearney (@vincekearney) May 8, 2022
Lewis rules out border poll
Meanwhile Mr Lewis appeared to rule out calling a border poll, saying that while the first nationalist first minister is a significant moment, its vote overall has not grown and the unionist vote remains larger.
Also speaking on the same BBC programme, DUP MLA Jonathan Buckley responded saying his party stood on a promise to remove the Protocol.
"Let me be very clear ... either the Secretary of State wants an Executive or the Protocol, but he can't have both," he said.
"The Secretary of State has a very clear choice."
Sinn Féin MP John Finucane said he was shocked anyone could deliver a message that the return of the Executive can wait amid a cost-of-living crisis and needed health service reform.
"There's over £300 million sitting there, ready to go into people's pockets, and I think it's incumbent that we sit down collectively, because that's what people want," he said.
Mr Buckley said it had been "quite a good result" for the DUP, particularly given some predictions that his party could drop to 18 seats.
He called for unionism to have a conversation with itself, adding "divided unionism in 2022 cannot win elections".
Alliance MLA Sorcha Eastwood said it had been a "fantastic election" for her party, doubling their MLA count.
"It's not just a brilliant day for Alliance, it's a good day for Northern Ireland as well because people came out and voted positively and that's a really important thing that shouldn't be lost in the noise," she said.
UUP MLA Robbie Butler backed his leader Doug Beattie, who had a close run in Upper Bann to retain his own Assembly seat.
Mr Butler said Mr Beattie had been leader for less than a year before the election, he insisted his message is strong, and described him as an "excellent leader", vowing to continue to offer positive unionism.
SDLP MLA Matthew O'Toole said his party had been on the wrong side of the tide in this election.
He described a move within nationalism for Sinn Féin after the DUP "behaved appallingly" in the pre-election period by refusing to confirm whether they would nominate a deputy First Minister to serve with a first nationalist First Minister.
Mr O'Toole said the SDLP had run a positive campaign with great candidates, but added: "Unfortunately it didn't work for us this time."
Additional reporting Conor Macauley, Sinéad Hussey