Gov. Charlie Baker will call for a nearly $190 million rescue plan for the MBTA as part of a proposed budget that will be unveiled tomorrow, the Herald has learned.

That plan represents a better than 50 percent hike in annual state aid for the beleaguered transit system, and comes as administration officials acknowledge that their total budget proposal could mean cuts in other state services, given a possible $1.5 billion spending gap they’re facing.

Baker’s proposal, described by aides yesterday, would push direct payments going to the T to $187 million for next fiscal year, a 53 percent boost from the $122.5 million the state is spending this year.

The $64.4 million hike, officials acknowledge, is a rare increase in Baker’s first budget plan in the Corner Office, which is pushing for early retirement of as many as 4,500 state workers, among other cuts.

But Stephanie Pollack, Baker’s transportation secretary, said the transit agency’s disastrous winter — marked by days of system-wide closures, shuttered rail lines and fuming commuters — made it clear some investment was necessary, even as Baker has pledged not to raise taxes or fees.

“We need to get a handle on the structural deficit, and there needs to be a sustainable long-term plan so that the T can operate in the revenue it has available to it. This fiscal year was not the year to tackle that type of challenge,” Pollack said in an interview.

“We’re giving them this money this year because there’s a problem to be fixed,” she said, “not because we believe the general fund has an obligation to fill in the operating deficit at the T.”

A pair of ongoing probes of the MBTA — one by a panel named by Baker, the other by officials from other urban transit agencies — are expected to offer up a raft of fixes by the end of this month; Pollack said the added T funds could cover recommended purchases and improvements.

A $125,000 so-called “peer review,” which officially started yesterday, includes officials from agencies in New York, Chicago, Toronto, Philadelphia and New Jersey, who will make what Pollack called “winter-specific recommendations.”

Baker is also floating the creation of an MBTA “weather resiliency fund,” to sock away money for weather-related costs. He wants to increase MassDOT’s budget by $44 million, including an extra $22 million for snow and ice removal.

In all, Baker will recommend hiking total transportation funding by $109 million over last year, bringing it to $645.7 million.

Baker aides said they’re looking to rein in budget-busters, like spending at MassHealth, adding that a plan to offer early retirement to 4,500 employees would save tens of millions.