Families in Mid-Scotland and Fife could lose out on extra childcare promised by the SNP because local facilities may not be upgraded in time.
Education Secretary Mike Russell has admitted he cannot guarantee that all two-year-olds eligible for a childcare place from the beginning of August will actually get one.
The cost of delivering the policy has increased by a third to £61million and the minister has conceded it may go up again.
He told last Wednesday's Finance Committee in Holyrood that he could “not rule out a different figure at the end of the day”.
Mr Russell has admitted he is “still negotiating” with COSLA over the capital costs of providing 600 hours of childcare for around 15,000 two-year-olds across Scotland
The body representing councils has estimated the actual cost could actually be as high as £114million.
They believe the Scottish Government has made incorrect assumptions regarding the cost per square metre and the split of provision between local authority and private providers.
The SNP'S childcare commitment was first announced on January 7 without any real work having been done on the cost and how it would be implemented.
When the Children and Young People (Scotland) Act 2014 was passed on February 19 the Scottish Government still had no idea of the capital costs of the policy.
Scottish Conservative Mid-Scotland and Fife MSP Murdo Fraser said:
“The Scottish Government has clearly not thought through how this childcare policy will be implemented in August.
“It has taken five months for the Education Secretary to produce a capital figure, yet now he is admitting it could rise even further by many more millions of pounds.
“With just eight weeks until this key SNP policy is due to be implemented, it’s worrying that they cannot provide a cast-iron guarantee the buildings and facilities needed will be ready in time.
“Parents in Mid-Scotland and Fife will now be wondering whether their child will actually get the childcare promised by the SNP."