The radical shake-up of 14-19 education in Wales will fail if the funding crisis in secondary schools is not resolved, heads warned this week.
School leaders said they would be forced to axe jobs and cut courses after the Assembly government announced a 7.43 per cent cut in sixth-form budgets last month.
The vocationally led 14-19 learning pathways initiative, one of the government's flagship policies, is likely to be the biggest casualty.
Under the programme, to be introduced from September, schools and colleges will have to work together to give learners more options.
But secondary heads across Wales said collaborating could now prove too expensive. Many plan to reduce the number of courses on offer.
School leaders from Powys and Conwy last week wrote joint letters to Jane Hutt, the education minister, and her deputy, John Griffiths, warning that they would be unable to deliver the curriculum.
Powys secondaries have been put in an "impossible position" with a shortfall of Pounds 840,000. More than 30 teaching jobs could be axed.
TES Cymru has also seen a draft letter from Powys's secondary school governors that attacks the government for its "failure" to fund schools.
John Hopkins, head of Gwernyfyd High in Brecon, said his school would lose Pounds 32,000 as a result of the cuts, contributing to a total deficit of more than Pounds 130,000 - the worst he has seen in 14 years as a head.
"Our ability to deliver the 14-19 learning pathways has been diminished," he said. "We will no longer have the money for the youngsters to go to Coleg Powys."
David Wylde, head of Ysgol Aberconwy and chairman of Conwy secondary heads' association, said: "We were all taken aback by this cut. There's been no rationale, no explanation and no consultation.
"This will clearly affect some of our long-term plans to meet the 14-19 learning pathways."
Ifor Evans, head of Ysgol Dyffryn Conwy, said his school was facing a Pounds 276,500 deficit.
"Trying to achieve what is required under the 14-19 partnerships will leave us in an impossible situation," he said. "Unless we get more money, we will not be able to do the learning pathways at all."
Post-16 curriculum cuts are also threatened elsewhere. Morriston Comprehensive in Swansea will lose Pounds 53,000, which could stop it launching new courses, according to its headteacher, Wayne Newton.
One head in Ceredigion, who did not want to be named, said he would have to cut at least four post-16 options from the timetable and merge several others.
Several heads told TES Cymru that feelings were running so high there had been calls for protests outside the Senedd, similar to last year's day of lobbying by primary heads over the foundation phase.
Gareth Jones, secretary of ASCL Cymru, a heads' union, said no direct action was planned, but the union would "consider every option to get our message across".
An Assembly government spokesman said the "difficult" budget round should not halt progress, and that a "considerable" Pounds 32.5 million annual investment would support the 14-19 networks.
He added: "The additional funding is instrumental in changing the pattern of spending in all learning settings and is helping to secure better achievement and opportunities for learners."
Around 40 teachers at Rhyl High School in Denbighshire went on strike yesterday over plans to close their sixth form, as staff at nearby Blessed Edward Jones RC High School voted on whether to join them in industrial action.
Catherine Britton, Blessed Edward's head, said she supported her staff, but also had a duty to her pupils: "If we strike, we will do so on a training day - April 20th."
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