Photo: The Canadian Press

Prime Minister Justin Trudeau speaks after announcing the government plans to build up to 18 new coast guard ships, in Vancouver, on Wednesday May 22, 2019.

The federal Liberals are shaking up the government's multibillion-dollar shipbuilding plan, promising $15.7 billion in new work to the two shipyards in Vancouver and Halifax while opening the door to their bitter rival in Quebec City.

During a news conference in Vancouver, Prime Minister Justin Trudeau said the government will buy two more Arctic patrol ships from Halifax-based Irving Shipbuilding and 16 so-called multi-purpose vessels from Seaspan Shipbuilding in Vancouver.

The ships will be built for the Canadian Coast Guard and aim to do two things: provide the coast guard with desperately needed new ships and prevent layoffs at Irving and Seaspan, which together have won billions of dollars in federal work since 2011.

Yet Irving and Seaspan are unlikely to be popping champagne bottles: Trudeau also revealed the government plans to hold a competition to add a third shipyard to the shipbuilding plan.

That opens the door to Davie Shipbuilding becoming an official partner in the strategy after years of intense lobbying, which Irving and Seaspan have long opposed for fear their Quebec City rival will steal work away from them.

Today's announcement in Vancouver, which was to be followed by similar announcements by ministers in the Halifax and Quebec City areas, comes only a few months ahead of the federal election, during which the Liberals will be looking to win or hold onto seats in all three cities.