Modeling shows that cases of Covid-19 in Ontario, Canada's most populous province, could treble by the end of May unless harsh restrictions are imposed, the Canadian Broadcasting Corp said on Friday.
Ontario Premier Doug Ford, under increasing criticism for how his government has handled the pandemic, is due to make an announcement at 2:30 p.m. Eastern Time (1830 GMT).
Some major hospitals say they are already close to a breaking point as a rapidly worsening third wave rips through the province, which accounts for 38% of Canada's population.
Ontario announced a record 4,736 daily cases on Thursday and the CBC cited sources saying this could rocket to 18,000 by end-May if current trends continued.
The head of the main nurses organization in Ontario is demanding a complete lockdown, including a curfew, but Ford has so far resisted such wide-ranging steps.
Separately, a group representing doctors urged authorities to take "extraordinary measures." The Canadian Medical Association (CMA) said the 10 provinces should band together to pool resources and allocate them where they were most needed.
"We are at a critical juncture where a truly national approach to combating Covid-19 will make the difference between more or fewer lives saved," CMA President Dr. Ann Collins said in a statement.