Ottawa is poised to spend millions on a Winnipeg Transit repair program Mayor Brian Bowman promised to scale back during his re-election campaign.

The federal government has agreed to share a $2.8-million contribution toward repairs to Winnipeg Transit's existing Fort Rouge garage, Bowman's office confirmed Monday.

Prime Minister Justin Trudeau is slated to make the announcement on Tuesday, municipal sources said.

The city is planning to make $11.5 million worth of improvements to the Fort Rouge transit garage's roof and ventilation system, $9.5 million on a hoist replacement at the same garage, $7.5 million on other Fort Rouge and Main Street garage refurbishments and $1 million on transit's heavy shop over the next five years.

City council asked Ottawa for help with these projects in July when it approved an application through the Public Transit Infrastructure Fund.

Three months later, during Winnipeg's election campaign, Mayor Brian Bowman promised to take $4.1 million from the transit-garage ventilation budget and spend this money on 55 new heated bus shelters over the next four years.

The mayor's office said Tuesday's announcement won't affect Bowman's election commitment.

The union representing Winnipeg Transit workers criticized Bowman's promise in October.

"We support measures proposed by the mayor to improve the comfort of riders through stop and station upgrades. However, these supports should not come at the cost of necessary facility upgrades, which the city will only have to pay for later in the form of future upgrades or increased maintenance costs," Amalgamated Transit Union Local 1505 president Aleem Chaudhary said in a statement at the time.

Trudeau, meanwhile, is expected to speak in Winnipeg while he faces scrutiny over allegations his office pressured former attorney general Jody Wilson-Raybould to help Quebec engineering firm SNC-Lavalin avoid criminal prosecution.

Federal Ethics Commissioner Mario Dion will investigate the allegations, first raised last week by the Globe & Mail.