The DUP will not nominate a speaker when the assembly is recalled next Tuesday.
Party leader Sir Jeffrey Donaldson said he required “clarity and certainty” from a new prime minister on their approach to the protocol before making further decisions.
The protocol is a trade deal which was agreed between the UK and EU as part of Brexit.
Due to concerns the DUP has with the agreement, it has refused to re-enter power sharing, or nominate a speaker, since the assembly election in May.
The SDLP successfully gained support for a recall petition to nominate a speaker from the Alliance Party and Sinn Féin.
The assembly cannot operate business as usual without a speaker in place.
Earlier this week, the Northern Ireland Protocol Bill passed its final hurdle in the House of Commons and will now move to the House of Lords.
Speaking to UTV, Sir Jeffrey Donaldson welcomed the progress of the legislation, but said “it remains to be seen” what decisions either Rishi Sunak or Liz Truss will take in relation to the Protocol Bill, if elected to be the next Conservative Party leader.
“We’re engaging with the two leadership teams at the moment in Westminster to ascertain what their plans are,” explained the DUP leader.
“We’re not in a position at the moment to take decisions on the next steps for us.
“We want to know we are moving towards a solution on the protocol, because that is what is creating political instability in Northern Ireland, that is the cause of the breakdown in the consensus that is required for power sharing to work.”
As for next week’s assembly sitting, the Lagan Valley MP said: “Let’s not pretend the problem isn’t there or apply a sticking plaster, that won’t solve anything.
“We need a real solution on the protocol so that power sharing can be restored on the basis of consensus.
“That’s the only way it can work effectively,” he added.
Meanwhile SDLP MLA Matthew O’Toole called for the DUP leader to “make up his mind”.
“People and families across Northern Ireland are experiencing the most severe cost of living crisis in living memory,” he added.
“At a time when working households are facing a real emergency, there is no justification for those continuing to hold our democratic institutions to ransom for their own cheap political games.”