Parents, teachers, politicians and unions have joined forces to oppose predicted Government 'real-term' cuts of £49m to Birmingham schools by 2020.
The shortfall will see a funding reduction to 99 per cent of city schools.
It represents an average loss of £293 per pupil and is equal to 1,038 teachers.
Campaigners argued city schools are already struggling to keep within their budgets having 'shouldered the burden' of wider public service cuts in the face of growing problems around mental health and special education needs.
They blamed the Government's 'fairer' funding formula and now they are mobilising to put pressure on the Department for Education to address the situation ahead of Chancellor's budget announcement in a matter of weeks.
Jack Dromey, Labour MP for Erdington, led the school summit at Birmingham City Council house on Friday where he told more than 100 supporters that schools would be forced to axe teachers, assistants, make 'heartbreaking' changes to the curriculum and warned that vulnerable pupils would be hit the most.
He said: "There are pockets of deprivation across the city.
"For so many parents everywhere their kids' life is tough enough and schools matter.
"We have to make sure the ladder is not knocked away from them.
"That's what is at risk here for a whole generation."
Cllr Ian Ward, leader of the Labour-run city council, backed the campaign and stated the formula meant some Birmingham schools would be hit to the tune of up to £513 per pupil comparing far worse to Conservative-controlled areas such as the likes of Hampshire.
He said: "We all know that school funding cuts are short-sighted leading to increased class sizes, a loss of staff, cuts to the curriculum.
"Education is about an investment in our children, our city and our country.
"It is about investing in all of our futures.
"Sadly this Tory Government knows the price of everything and the value of nothing.
"It's clear the Government has got this wrong."
Cllr Brigid Jones, deputy leader, told the audience she had saw first-hand that teachers' jobs were getting harder during her five years as cabinet member for children's services.
She said: "Due to service cuts elsewhere so much has fallen on your shoulders.
"It is a burden you have carried very well. But there is a limit to how much we can put on you.
"These cuts are unacceptable and unsustainable."
Cllr Jones also called for a united campaign stating that some teachers in the profession mistakenly believe there is enough money to go around and it just needed 'reshuffling'.
She added: "That is fundamentally not true.
"The sum total of money in this system is not enough for our city's schools.
"I have seen some fighting and disbelief of that. We need to be united against the common enemy which is the Government choosing to make cuts.
"Most of you here get it but some don't.
"If we in-fight we will get nowhere."
The National Association of Head Teachers was among unions represented at the summit.
National secretary Rob Kelsall declared Government claims that overall education spending had increased were a 'complete myth' which had been 'blown apart' by the Institute For Fiscal Studies.
He went on to describe the situation as a 'crisis of their making'.
Members of action group Save Our Schools, which launched last year, spoke of the importance of parents joining teachers and politicians in the campaign.
While Anderton Park School headteacher Sarah Hewitt-Clarkson said parents throughout the city are having to fundraise for basic school supplies.
She also argued that the campaign had already achieved a 'small victory' in pressuring the Government to reduce the cuts from around £90m to £49m.
Tracy Brabin MP, shadow minister for early years, closed the summit after criticising the cuts to local councils - including Birmingham - which have resulted in closures to more than 1,000 Sure Start Children's Centres throughout the country.
In response a Department for Education spokesperson said: “Every school attracts more funding per pupil through the National Funding Formula and there is more money going into schools than ever before, rising to a record £43.5 billion by 2020 – 50 per cent more in real terms per pupil than in 2000.
"Birmingham received £909 million for its schools this year 2018-19, which is a £4m increase on 2017-18.
“We know that we are asking schools to do more, which is why the Education Secretary has set out his determination to help schools reduce the £10 billion spent each year on non-staffing costs.
"This includes helping schools to save millions of pounds by using government-backed deals for things like energy and water bills or printers.”