The Health Minister is coming under pressure to scrap recommendations to move children's heart surgery out of Belfast.
Parents fear that lives could be lost if a children's heart surgery service is based a 100 miles away in Dublin.
The UUP has proposed a motion to be debated at Stormont this week on the proposals to move the services. The party's health spokesman Roy Beggs jnr said: "It's like any medical emergency, there are better outcomes with early intervention. Delays in carrying out procedures can result in adverse outcomes affecting children."
The mooted closure of the life-saving surgery facility moved a step further last month, after the Health and Social Care Board recommended a shift south of the border.
Last year a UK-wide report said that centres must perform a minimum of 400 children's surgical procedures each year. Around 110 heart operations are carried out annually at Belfast's RVH for children who travel from across Northern Ireland and border counties as far away as Donegal. Additional heart surgery procedures are also provided for adolescents.
However, the final decision lies with Edwin Poots. The Assembly motion calls for Mr Poots (left) to reject the recommendation of a Dublin-only service, keeping all routine and emergency paediatric heart operations in Belfast.
Mr Beggs has slammed consultation on the plans, drawing parallels with the handling of plans to close care homes here. However, UUP MLA Robin Swann said he was encouraged by the length of time Mr Poots is taking to announce his decision.
The North Antrim MLA – whose three-month-old son Evan is due to receive heart surgery at the Royal soon – added: "We will see his response in tomorrow's debate."