Primaries and secondaries could be sucked into the budget crisis threatening to engulf their state-funded nursery counterparts, a funding expert warned this week.
There are fears that maintained nursery schools could lose up to a quarter of their budgets under new early-years funding arrangements due to be introduced in April.
George Phipson, a National Association of Head Teachers (NAHT) consultant, expects it to become a major political issue if state nurseries - 87 per cent of which are rated good or outstanding - suddenly find their funding slashed in the run-up to a general election.
He warns that in those circumstances local authorities, who are now devising the new early-years formula, will look elsewhere in education to plug the gap.
"There are big implications for the whole schools system," Mr Phipson said. "If a local authority gets this wrong, then they are going to have to find the money from somewhere.
"And because there is no slack in the system, they may have to top-slice primary and secondary school budgets."
He said all schools have a chance to help avert disaster by getting involved with the early-years funding formula setting process taking place in local authorities, through their local schools forums.
Mr Phipson, due to speak at the NAHT's education conference this week, said he suspected many heads would be unaware of the problem. But he said: "All schools need to be engaging with this now."
The danger of the process going wrong was emphasised last week when Dawn Primarolo, children's minister, had to write to all local authorities reminding them of the "high importance" of maintained nursery schools, which she said often served deprived areas where needs were greatest.
"I am clear that a single funding formula should not be used as a vehicle to close, or close by strangulation, good quality nursery school provision," the minister wrote.
Mr Phipson said local authorities could create problems because of confusion over what creating an equitable funding formula meant.
If they interpreted that as meaning all providers should get the same funding per child, state-funded stand-alone nurseries would lose out as they had much higher overheads than other providers.
It was also likely to risk unfairly inflating the budgets of private, voluntary and independent (PVI) providers because they tended to have less qualified staff with lower wages.
The National Day Nurseries Association, which represents PVI providers, argues the change in the funding system is essential in achieving fair, more equitable early-years provision.