DUP leader Sir Jeffrey Donaldson said he will not leave the House of Commons to take up his seat in the Assembly until issues around the Protocol are resolved.
The DUP leader was elected to Stormont in the Assembly elections last week, but there had been uncertainty over whether he would take up his position as an MLA or remain at Westminster.
Sir Jeffrey Donaldson has reiterated that without "decisive action" from the UK Government on the Protocol, he will not nominate Executive ministers.
The DUP leader's announcement comes after the Government stopped short of pledging to take action on the Protocol in the Queen's Speech.
Speaking in House of Commons on Tuesday evening, he said: "My party is absolutely committed to the future of the political institutions. We want them to work and to deliver for everyone in Northern Ireland
"I'm prepared to commit the remainder of my political career to going back to those institutions and working with my colleagues to make them work.
"But I have to say... I will not leave this House until this protocol issue is resolved. I will not leave this House until I can be sure that our political institutions in Northern Ireland have a stable foundation."
Speaking earlier on Tuesday Sir Jeffrey insisted that "words in themselves will not fix this problem" - adding "until we see that decisive action we won't be moving on the political institutions".
He continued: "I want that to happen quickly; it must happen quickly. It's in the interests of everyone that we get this sorted out, we find a resolution, and then we can move forward."
The speech contained a commitment to "take all steps necessary" to protect Northern Ireland's place in the UK internal market.
However, there was an emphasis placed on talks with the EU to find a resolution.
Earlier the Prime Minister Boris Johnson had described the situation with the protocol as "now very serious" during a call with Taoiseich Micheál Martin.
According to Downing Street, Mr Johnson also said that the "balance" of the Good Friday Agreement "was being undermined" by the protocol.
Sir Jeffrey also reiterated that he would announce by the end of the week whether he would resign his Westminister or Stormont seats, saying that " I will come to a decision with my colleagues."
Under current rules, it is illegal to hold both an MP and an MLA seat silmultaneously. Sir Jeffrey therefore must decide which of his two seats to resign from.Sinn Féin vice president and prospective First Minister Michelle O'Neill accused the UK government of "pandering to the DUP" over the protocol.
During a visit to the Ulster Hospital, O'Neill said the plight of staff there highlighted the need for an Executive to be formed immeadiately and said the actions of the DUP and the British Government "punishes the people."
The Alliance Party MP Stephen Farry warned against a "uniltateral move to scrap parts of the Northern Ireland Protocol", describing this strategy as "counterproductive."
Mr Farry called on the government to "abandon the vicious cycle of spin and briefings" on the Protocol, and instead focus on "mutually agreed, sustainable and legal solutions to the challenges posed."
UUP leader Doug Beattie said that the Protocol had to be "resolved as a matter of urgency so we can get back to Stormont and begin the job of delivering for the people of Northern Ireland who elected us, and focus on the economy, health care and the cost of living crisis."
Speaking ahead of the Queen's Speech, the SDLP's Matthew O'Toole described reports that Liz Truss was seeking to scrap parts of the Protocol as a "‘contemptuous rejection of democratic election"
Mr O'Toole said that the recent Assembly election displayed a "majority supporting the implementation of the protocol" and accused the conservative government of "using [Northern Ireland] as a casual distraction from their serious failures in government."
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