The annual budget of the Auckland mayor's office is bound by legislation. The Local Government Act 2009 specifies a minimum 0.2 per cent of the council's budgeted operating costs. For 2014-15 the operating expenditure budget for the council was $3.47 billion.
But Brewer, who worked inside the Auckland City mayor's office 14 years ago as a communications adviser to John Banks, says a quantum leap in cost-cutting is there for the taking.
"The mayoral office budget should and could be easily halved. It shouldn't cost $4m a year," Brewer told the Herald on Sunday.
"I would've thought $2m was more than enough - particularly when you think the office is supported by a huge service-based organisation that includes half a dozen council-controlled organisations and over 11,300 council staff."
With Brown due to end his embattled reign in October, Brewer says the successor should be voted in based on whether they want to cut costs - primarily by reducing the staff of the mayor's office.
"It doesn't need to have 21 staff drawing $2.3m in salaries nor does it need a raft of consultants and contractors invoicing nearly $600,000.
"But, alarmingly, that's the current model," Brewer said.
"Salaries are overwhelmingly the majority of the office costs, so if you just cut back the number of staff you'll shave the operational budget considerably."
In response, the mayor's office pointed to Brown regularly coming in under budget and that the rules were set by the Government.
"Government established a mayoral office budget including staffing by statute," a spokesman said. "Although that [0.2 per cent] was a minimum and the amount could be increased, the mayor has kept the budget to that minimum, never asked for more and consistently underspent the budget.
"He has also allowed the budget to be used for non-budgeted items that are considered important by the council. A recent example is the Ports of Auckland Future Study."
Leading mayoral candidate Phil Goff said he had received "a stream of public feedback" about how public money could be made to go further and cost-cutting would be at the core of his campaign.
"It's incumbent on council, including the mayor's office, to look for more efficiency," Goff said. "One of my major platforms ... will be we do things in the most efficient way. We eliminate waste and duplication.
"My reputation in central Government was always to be a bit of a Scrooge when it came to spending money on my own budget."
Goff said he was not prepared to commit to an "arbitrary" figure of what the budget needed to be.
Fellow mayoral candidate Vic Crone said council spending was "out of control".
"The mayor's office is yet another example, with both expenditure as well as the number of personnel too high."