Labour councillors on Sheffield Council are demanding the Government stop and think again about their funding policy for schools.
They are seeking to get the council's full backing at a meeting today, demanding the government rethinks is national funding formula.
The Department for Education is making changes to the way it funds schools to try and close the gap between different geographical areas, with some schools expected to receive more funding.
But analysis by teaching unions indicates 98 per cent of schools will face cuts in per pupil funding as inflation and school costs increase at the same time that funding per pupil is frozen.
Labour councillors are calling on all schools, parents and carers across Sheffield to write to the government and local MPs about the cuts to funding.
Coun Jackie Drayton, cabinet member for children, young people and families, said: "The government’s funding formula is divisive, unfair and pits schools against schools, local authorities against each other, and primaries against secondary schools.
“I am proud to be working alongside the trade unions, teachers, support staff, governors, parents and carers to get more funding for Sheffield schools”.
“I call on all from across the city who care about education to write to the government urging them to reconsider their school funding plans.
“The proposed new funding formula will simply redistribute a sum of money that is inadequate to support schools. Shockingly by 2019 Sheffield schools will see an average pupil funding decrease of around 10 per cent - approximately £350 per pupil."
Coun Craig Gamble-Pugh, who proposed the motion for council, said: "It is outrageous that schools across our city will be worse off. Schools are already struggling to manage budget deficits and there are shortages of teachers and a widening attainment gap between disadvantaged pupils and their better-off peers.
“We need new extra funding for our existing schools, and the government needed to do this with their recent budget. They rejected our calls but unforgivably found an extra £500 million for grammar and free schools instead, which we totally oppose.
“The Conservatives’ divisive policies are forcing schools to scramble for funding. Every child deserves the best possible start in life and we are calling for support for the More Funding for all Sheffield Schools’ Campaign.
“We are fighting for funding to be found for schools, not from the proposed redistribution of cash between local authorities or from taking money from primary schools to give to secondary schools, but for new money which is badly needed."
A DfE spokesman said school funding was at its highest level on record, at more than £40bn in 2016-17.
He added: "But the system for distributing that funding across the country is unfair, opaque and outdated.
"We are going to end the historic post code lottery in school funding and under the proposed national schools funding formula, more than half of England’s schools will receive a cash boost.
"Significant protections have also been built into the formula so that no school will face a reduction of more than more than 1.5 per cent per pupil per year or three per cent per pupil overall.
"We recognise that schools are facing cost pressures, which is why we will continue to provide support to help them use their funding in cost effective ways, including improving the way they buy goods and services so they get the best possible value."