A charity representing cancer patients has said it expects a "move toward resolution" when it meets the Transport Minister over Dublin-Donegal flights.
Donegal Cancer Flights and Services is concerned that changes to the Public Service Obligation (PSO) route will cut off a "medical lifeline" and "genuine same-day access" for cancer patients and others.
The group helps cancer patients with booking flights, counselling support and other information.
Donegal Airport has argued the changes to the route outlined in a new contract does not meet "the spirit or intent for a PSO route".
The changes will mean the Emerald Airlines aircraft will longer overnight at Donegal Airport, which it had done for 21 years.
Donegal Cancer Flights and Services said this gave confidence to patients who were relying on the morning flight.
The old midday flights are no longer to be provided and will be replaced by a 6.30am flight arriving from Dublin and an 8.30pm flight leaving Donegal.
A further 'listening exercise' will not be sufficient.
Donegal Cancer Flights and Services said that the changed timetable may leave no seats available at short notice - and drive up the price of tickets.
Darragh O'Brien has agreed to meet with charity representatives on Tuesday.
The group wants the Government to commit to "protecting reliable same-day and midday medical access under the PSO".
In a letter welcoming the meeting, the group said: "Your officials have already met with us. "They listened carefully and, we are assured, relayed our concerns to you in full. "We are therefore approaching this meeting not simply as another opportunity to restate the problem, but in the expectation that it will move toward resolution."
It added: "For cancer patients in Donegal, this is not a theoretical policy issue, it is a live access-to-care concern affecting real appointments, real costs, and real strain on vulnerable families. "A further 'listening exercise' will not be sufficient. We are looking for decisive ministerial leadership and tangible progress."
It continued: "We sincerely hope the meeting will allow you to outline clear next steps and, ideally, positive developments that demonstrate the Government's commitment to protecting reliable same-day and midday medical access under the PSO.
We look forward to constructive engagement and to working toward a practical solution."
The group had previously called on Mr O'Brien to "meet people on the ground" in Donegal who rely on the flights for their medical treatments, arguing that the schedule change was down to "people in Dublin making decisions that have no idea what it's like living in" the area.
Asked specifically if he will go to Donegal to meet cancer patients who use the flights, the minister said the meeting had already been arranged for Dublin.
He told reporters on Tuesday: "I don't reach into the public procurement, I don't set the tenders."
He added: "I intend to meet with the groups from Donegal myself, and I will do that and listen to them, listen to their concerns around the new schedule, and see what we can do to resolve it."
Asked about the dispute, Health Minister Jennifer Carroll MacNeill said it was her preference to expand services within Donegal.
"My bigger question is why it is necessary to travel to Dublin? "I appreciate it's actually, in many cases, nearly faster than getting to Galway, having regard to the geography of the region. "But of course, Galway is the centre for that region, and I'm trying to expand services within Letterkenny. "I made a decision to put a surgical hope there, that I which was important for breast cancer researchers, for example, that I approved the allocation of additional oncology chairs. "So what I would like is for the people of Donegal to get their cancer treatment as far as treatment as far as possible within Donegal, and not have to be concerned about flights or trains or cars or anything else, to have to go to Dublin."