Britain's biggest union has threatened strike action if any members are made redundant through an education cash crisis.
Last week The Argus revealed how heads in Brighton and Hove had refused to accept their budgets from the city council because they thought them so low.
Some said they did not see how they could avoid staff cuts.
Unison represents most support staff such as classroom assistants, caretakers and administrative workers.
Brighton and Hove Unison secretary Alex Knutsen said: "My branch will ballot for strike action should any of our members be threatened with compulsory redundancy. We will fight to protect jobs and the education service."
Mr Knutsen blamed the crisis on Education Secretary Charles Clarke and the Government.
He said schools were receiving millions of pounds less than they should and that council managers said redundancies could not be ruled out.
After a poor grant settlement, the Government had allocated an extra £1 million for city schools but this was an insult.
Mr Knutsen said the council should meet those involved in schools to discuss a strategy for protecting education.
The union last year put in a claim for £2,000 Brighton weighting payments to all staff, including those in schools.
Brighton Pavilion Labour MP David Lepper said he and other MPs had lobbied the Government for a better grant to the city council.
As a result almost £1 million was granted this month, as reported last week by The Argus.
Mr Lepper said it was not true to say that the Government had transferred resources from the South to the North. This was a crude assessment of its motives.
He has asked schools director David Hawker to look at the sums and give a detailed assessment of what the shortfall might be so that a case could be put.
Mr Lepper said: "We do believe there is a case for more funding for Brighton and Hove."
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