The Democratic Unionist Party (DUP) leader has told his party that they will not nominate a new Speaker when Stormont is recalled on Tuesday.
Assembly members are due to meet in a further bid to elect a Speaker so they can implement a new organ donation law.
They were urged to act by the family of a child who needs a heart transplant.
Sir Jeffrey Donaldson said it was “disgraceful” that organ donation was “being used as blackmail for the return of devolution”.
He made the comments in a letter to party members over the weekend in which he explained that the DUP would not be pressurised into dropping its boycott of Stormont until its concerns over the Northern Ireland Protocol are resolved.
“We will not be nominating a Speaker on Tuesday,” Sir Jeffrey said in his letter, first reported by the PA news agency.
“Westminster is sovereign and can resolve the issue quickly.”
The Northern Ireland Assembly cannot carry out its business without a Speaker in post.
The assembly has not fully functioned for just over a year, after the DUP pulled its first minister out of office last February, in protest over the protocol.
Assembly members have already met several times to elect a Speaker but each bid has failed.
SOURCE: BBC