The North's first minister in waiting, Michelle O'Neill, has said there can be "no excuses" to prevent an Executive being formed in Northern Ireland.
Addressing reporters at Stormont on Monday afternoon, Ms O'Neill said there was "no reason for delay" and said that "as democrats the DUP, but also the British government, must accept and respect the democratic outcome of this election.
"Brinkmanship will not be tolerated for the north of Ireland to become collateral damage in a game of chicken with the European Commission. "
The responsibility for finding solutions to the protocol and ensuring its smooth implementation "lie with Boris Johnson and the EU," she said. "Make no mistake, we will not be held to ransom."
Ms O'Neill was speaking a meeting with the Northern Secretary, Brandon Lewis earlier on Monday, and said she had also spoken with the Taoiseach and would be engaging with other party leaders.
She also said that in their meeting with Mr Lewis Sinn Féin had raised the outstanding issue of Irish language legislation, and were told there would be a reference to it in the queen’s speech on Tuesday. The Queen announced on Monday night that she has delegated the reading of this speech to her son Charles due to mobility problems.
“That legislation will be rolled forward very, very soon,” Ms O’ Neill said. “We don’t have a precise date but we have a very precise commitment … that legislation will be brought forward soon.”
Speaking alongside her party colleague, the Sinn Féin leader Mary Lou McDonald said the “job now is to get to work” and called for the “immediate formation of an Executive, Michelle O’Neill ratified as first minister and an appointment of a deputy first minister.”
She warned "any tactics of delay from the DUP, any grandstanding by them, any gamesmanship from the British Government who may wish to use the north of Ireland as a bargaining chip in terms of their wider engagement with the European Union over the protocol, would be clearly intolerable and must not happen."
Mr Lewis is holding meetings with the leaders of the main Stormont parties in an attempt to form a power-sharing government following an Assembly election which returned Sinn Féin as the largest party.
The DUP, which was returned as the second largest party, resigned from the position of first minister in February as part of its protest over the Northern Ireland protocol, which it opposes.
The DUP leader Jeffrey Donaldson has said his party will not go back into the Executive unless the protocol is replaced.
The DUP is not expected to nominate a deputy first minister when the new Assembly meets for the first time this week, which means Ms O’Neill cannot take office as first minister and other ministers cannot be appointed, which would create stalemate at Stormont.
Outgoing ministers can sit in a caretaker role for up to 24 weeks but with limited powers.
Speaking after his own party’s meeting with Mr Lewis, Mr Donaldson called again for the UK government to take action on the protocol and said it must be removed before an Executive could be formed.
He said his party had made their position “clear” and it was “the position we have held before the election, throughout the election campaign and will continue to hold, and that is until we get decisive action taken by the UK government on the protocol we will not be nominating ministers to the Executive.
“We want to see stable political institutions, we want to be part of the Executive, we want to play our part and fulfil the mandate we were given by the people of Northern Ireland,” he said, adding that “ware also clear given the damage and harmful impact the protocol continues to have on Northern Ireland, driving up the cost of living, harming our economy, impeding the ability of businesses to trade with our biggest market and fundamentally undermining political stability, undermining the principle of consensus politics.”
“We need this to be resolved,” he said.
Other parties were at Stormont on Monday on what was their first opportunity since the election last week.
The Alliance Party leader Naomi Long, whose party dramatically increased its representation at Stormont and took 17 seats, said they were turning up for work as promised during the campaign.
“I want us to sit down, get the negotiations under way on the programme for government and the budget, and I want to see us getting government up and running as quickly as possible,” she said.
Calling on the DUP to “step up to the plate” she warned the party it would be “foolhardy for them to overplay their hand with devolution because that is a gamble that Northern Ireland can’t afford to take.”
The SDLP leader Colum Eastwood urged the DUP to "get on with it today and form a government."
Mr Eastwood - whose party lost four seats, including that of the outgoing minister for infrastructure, Nichola Mallon, to return eight MLAs - said his party would not nominate a replacement for Ms Mallon.
He said it would be “totally undemocratic for us to sit in a zombie Executive and have no power to do anything when we haven’t even got a mandate from the people.”
The SDLP, he said, would now go into opposition. “We will act constructively, work with other parties but we will also hold ministers to account where we have to,” he said.