The MBTA wants to slash as many as 72 jobs and outsource its much-maligned "money room" to a private contractor, a move officials say will eventually reap more than $5 million in annual savings.

Officials at the cash-strapped agency will ask the MBTA's Fiscal Management and Control Board tomorrow to approve a plan to hire the Virginia-based Brink's Company to handle the T's cash collection operations.

The proposal — which would pay Brink's $3.6 million a year for at least two years with options — would mark the first move by the T to privatize part of its system since lawmakers gave it more flexibility to seek outside contracts under a three-year reprieve from the so-called Pacheco Law.

If approved, the T could transition to the private contractor in roughly four months. T officials say they're recommending the bid over another from GardaWorld, which pitched its services at $4.7 million annually.

But a fight is already forming from unions. A half-dozen members of the Carmen's Union Local 589 crashed a briefing T officials organized for reporters this afternoon, where they showed up uninvited and quietly sat in on a presentation from acting general manager Brian Shortsleeve.

"We understand this is controversial, we understand that these sorts of changes are not easy," Shortsleeve said, as union members listened from the other side of the room. "There's a very active dialog. It will continue … (But) we are committed to doing what needs to be done to put the MBTA on a path to fiscal sustainability, and utilizing the flexible contracting rights we got from the legislature is a really important part of that."

In hiring Brink's to handle and transport nearly $200 million in cash annually, the T would also cut 72 jobs at the Charlestown-based facility. Union employees have the option of moving back into bus-driving jobs, but it's unclear how many actually will.

Shortsleeve said the agency is hiring on average more than a dozen bus drivers a month, meaning the T could quickly absorb the workers and start to see the estimated savings below the $9 million it currently spends on supplies, salaries and healthcare costs annually at the money room.

Shortsleeve said when factoring in long-term commitments, like retiree health and pension costs, the T spends as much as $11.8 million operating the money room itself.

The facility has come under fire for months after T officials launched an audit that found a series of security lapses, including duct-taped doors, broken vault locks and what auditors described as a lax culture among employees.

The Herald reported last week that the Carmen's Union had sent letters to potential bidders warning them that the union could take "legal action" to stall the contract if its labor agreements weren't honored. The T has rejected the union's argument.

The T also released a photo last week to the Herald showing a money room employee laying on the floor on a yoga mat, as wads of cash lay on a table nearby. Jim O'Brien, president of the Carmen's Union, claims that the employee is not a member of his union but a supervisor.

Speaking to reporters after the briefing, O'Brien also rebuffed the T's figures, saying he believes there are fewer than 50 — not 72 — workers currently working in the money room and that it will likely be even less after a round of retirements.

"This is not a transparent process," O'Brien said. "It's like this has already been decided, in the way he (Shortsleeve) makes it sound. … That's not transparency."