London's fire authority will hold an emergency meeting today in the latest stage of a row over possible 12 fire station closures and 520 job losses in the capital.
Boris Johnson has also proposed cutting 18 fire appliances in the cost cutting move, which has seen stiff opposition from some members of the London Fire and Emergency Planning Authority.
The authority last month rejected proposals which aim to make £45 million of savings.
Members narrowly decided to hold a public consultation on future plans, without involving closures.
But London's Mayor Boris Johnson stepped into the dispute by taking the unprecedented step of directing the authority to move towards a consultation on cost-cutting measures.
He said the authority had increased the likelihood of compulsory redundancies by not tackling a budget gap.
London fire commissioner Ron Dobson has proposed cutting around 10% of frontline firefighter posts, adding that he hoped to avoid compulsory redundancies.
The number of fire stations would be reduced to 100 under the proposals.
He said the number of fire incidents in London was down by a third in the past decade, with fire appliances only used seven per cent of the time.
A total of 24 fire stations dealt with two or fewer incidents a day, while the average firefighter was called out to 195 incidents a year, with only 48 of those involving fires, he said.
The Fire Brigades Union (FBU) called on members of the authority to "hold their nerve" and continue to oppose cuts.
Regional secretary Paul Embery said: "They were right to reject the cuts at their previous meeting and we think they should do so again.
We do not believe they are under any legal obligation to comply with the Mayor's authoritarian demand."
FBU general secretary Matt Wrack said thousands of firefighters' jobs were under threat across the country with the possible closure of up to 70 fire stations because of spending cuts.
"These are horrific attacks on the London fire brigade and are part of a wider onslaught against the fire service as a result of the Government's austerity measures. We will fight these cuts every step of the way."
If the authority votes against the proposals Mr Johnson could challenge the decision in court.