Canada on Thursday unveiled a framework for a universal drug plan that, once fully implemented, would mark the biggest expansion of its publicly funded health care system in decades.

The government said it would start by covering the costs of contraceptives for up to 9 million Canadian women and diabetes medications for nearly 4 million Canadians, and add more drugs to the regime as it is rolled out over the coming years.

New legislation also outlines Ottawa's plans to work with provinces to improve prescription drug accessibility and affordability, including by setting up a national formulary and buying medications in bulk at cheaper rates.

"Today is a giant step forward for our health system," Health Minister Mark Holland told a news conference.

The pharmacare plan -- as it is locally termed -- follows protracted negotiations between Prime Minister Justin Trudeau's liberal minority government and a small leftist faction in parliament.

The New Democratic Party (NDP) agreed to prop up the Liberals until the fall of 2025, on the condition that the government immediately launch the drug program, which was first recommended by commission in 1964.

"Far too long, millions of Canadians have struggled to afford the prescription drugs they need to stay healthy and in some cases, even alive," said NDP Member of Parliament Don Davies. "Today that changes."

A recent OECD report using 2021 data found that Canada spends more per capita on medications than all but three member countries -- Japan, Germany and the United States.

Crucially, however, the plan also requires the support of Canada's provinces, which are responsible for administering health care. Alberta and Quebec have already said they would opt out.

Conservative opposition leader Pierre Poilievre, who leads Trudeau in public opinion polls, has called the proposed plan unnecessary, noting that most Canadians have the costs of pharmaceuticals covered through their workplace or social services.

The nonprofit Council of Canadians said recent polling found two out of three Canadians support the creation of a public, universal pharmacare program.

The pharmacare proposal comes on the heels of the government's rollout of a federal dental plan and a Can$10 per day daycare plan.