The five largest parties at Stormont have written to the Northern Ireland Secretary urging him to intervene to process a new organ donation law.
The opt-out system was passed by MLAs at Stormont last year but the enacting of the legislation has been delayed due to the political stalemate.
It was to be named Daithi's Law after six-year-old Daithi MacGabhann, from Belfast, who is on the organ transplant waiting list and whose family have campaigned for the new legislation.
Read more: Delay in introducing Daithi's Law branded "unacceptable"
His father Mairtin said he is devastated the law has been delayed, and has written to Chris Heaton-Harris asking for an urgent meeting.
On Thursday, the larger Stormont parties announced they had united to write to Mr Heaton-Harris asking him to step in and legislate to allow Daithi's Law to be enacted as soon as possible.
Mr Heaton-Harris said later on Thursday that he would be very happy to meet with the MacGabhann family.
"I understand the importance of the issue concerned, health is devolved, it is really disappointing that they are waiting for the legislation to go through that should be going through the Assembly," he told media attending the British Irish Intergovernmental Conference at Farmleigh House in Dublin.
"But I will meet them as soon as I can, and look forward to talking to them."
The law, which would bring Northern Ireland into line with the rest of the UK, would automatically make people organ donors unless they specifically state otherwise.
The letter, signed by Sinn Fein Stormont leader Michelle O'Neill, DUP leader Sir Jeffrey Donaldson, Alliance leader Naomi Long, UUP leader Doug Beattie and SDLP leader Colum Eastwood, was also copied to Department of Health permanent secretary Peter May.
The leaders write: "It has become clear that further legislation is needed for the opt-out system to become fully operational.
"As leaders of the five main parties, we write to ask that your department works with our Department of Health and legislates in Parliament to ensure this new system for organ donation can be operational as soon as possible.
"We understand that the Department of Health has draft legislation prepared which could enable the law to be operational by the spring of 2023."
The powersharing Assembly at Stormont has been suspended from last year as part of a DUP protest against the Northern Ireland Protocol.
A Northern Ireland Office spokesperson said: "The Secretary of State is aware of how important this life-saving legislation is to Daithi, his family and people across Northern Ireland, and will meet the family on this important issue.
"If an Assembly were sitting, this matter could be resolved swiftly and the Secretary of State asks the Northern Ireland parties to realise the unacceptable impact that the lack of locally accountable political leaders is having on fundamental issues in Northern Ireland."
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