Parents have accused John Swinney of "punting" concerns about a major capacity blunder at a Renfrewshire school on to the education secretary.
The Deputy First Minister said he would "happily" meet Neil Bibby MSP and worried constituents after botched sums left Dargavel Primary in danger of being oversubscribed in a matter of years.
The school in Arrochar Drive, Bishopton, has an intended maximum of 548 pupils, but analysis suggested space could be needed for as many as 1100 in the catchment area in the future.
Previous sums predicted the register would not exceed 430.
A review has been ordered by the council in a bid to get to the bottom of the saga, while a short-term fix of six modular classrooms – at a cost of around £2million – was signed off by councillors last week.
Despite Swinney confirming at FMQs on Thursday that he was willing to meet parents, a Scottish Government email seen by the Local Democracy Reporting Service said Shirley-Anne Somerville, Cabinet Secretary for Education and Skills, will be "taking this forward".
It is likely that any such meeting would take place at the end of January.
Alan Kelly, chair of Dargavel Primary School Parent Council, said: "The biggest disappointment is his failure to even grasp the size of the situation.
"This isn't just an education matter, it's not just that a school has been built slightly too small.
"There's been a total abject failure within Renfrewshire Council's ability to plan and it's the consequence that has an impact at a Scottish Government level wider than education."
He claimed a second school would be required and echoed suggestions from opposition councillors that such a scenario would cost tens of millions of pounds.
Mr Kelly added: "The long-term consequence is that the school is far too small.
"They're going to have to build at least an additional one school.
"Estimates are that that's going to cost £20million and Renfrewshire Council can't find that out of nowhere.
"That's really where we're hoping that senior members of Scottish Government would get involved, because if they don't and they leave it to Renfrewshire Council, it's not only going to impact Dargavel Primary, it's going to impact every school in the council and it's going to impact all council services, because they have to find £20m from somewhere and it can only come from cuts.
"Alternatively if the Scottish Government gets involved then there's opportunities to increase the council's budget.
"John Swinney stood up in parliament and got the kudos by saying he would meet constituents, but very quietly he punts it to the education secretary because it's an issue about a school.
"That was really disappointing."
A Scottish Government spokesperson said: "We have been in urgent contact with Renfrewshire Council, who are responsible for managing their school estate.
"Scottish Government officials continue to engage with the parent council to set up a meeting at a time that is suitable for all parties."
When contacted, Renfrewshire Council said it had nothing to add at this stage.
However, a spokesperson previously said: “Councillors on the education and children’s services policy board have agreed an external review will investigate the circumstances behind the error into the projected school roll for Dargavel Primary School and lessons which can be learned in the future.
“Details of this will be provided as soon as this is confirmed.”
Steven Quinn, director of children’s services, has already apologised to those affected by the situation.
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