The appeal for a new £9m cafe at the top of Snowdon faces a serious shortfall, a leaked report claims.
The appeal deadline is to be put back for a second time
The Snowdonia Summit Appeal Campaign was supposed to close next Friday, but organisers look set to extend the deadline for a second time.
The closing date for the last £1.7m of the appeal was first set for June but was put back due to lack of support.
The report revealed to BBC Wales claims a bid for a £750,000 Heritage Lottery Fund grant has also failed.
About 350,000 people visit Snowdon each year, but its 70-year-old summit cafe is seen as outdated, and was once called "the highest slum in Wales" by Prince Charles.
The leaked report is to be discussed by park authority members on Wednesday.
The report claims that the appeal "continues to attract a trickle of funds but despite further direct approaches to potential funders, no new major sponsors have come forward".
The old concrete cafe was called a 'slum' by Prince Charles
The document shown to the BBC said the Heritage Lottery Fund support for the appeal was also likely to be limited to projects promoting access and learning rather than building the cafe.
Discussions between the authority and the Snowdon Mountain Railway have also been difficult, according to the report.
It said the company, while supporting the project, was worried about the impact the construction work could have on its business.
The replacement building for the current cafe would also include a visitor centre and new Snowdon Mountain Railway terminus.
Snowdonia Summit Appeal Campaign - a partnership between the Snowdonia National Park Authority and the Snowdonia Society - has collected £7.3m from the public and private sector but needs another £1.7m.