Canada's ruling Liberals, who a few weeks ago looked certain to lose an election this year, are mounting a major comeback amid the threat of U.S. tariffs and are tied with their rival Conservatives, according to three new polls.

Race to replace Prime Minister Justin Trudeau’s government is suddenly competitive after U.S. president calls for tariffs and says Canada should be the 51st state.

Voters in Canada's most populous province, Ontario, head to the polls on Thursday in an election where the incumbent premier seeks to use U.S. tariff threats to expand his majority. Progressive Conservative Party leader Doug Ford called an election more than a year early,

Ontario is Canada’s most populated province and is expected to grow to 21.7 million this year, more than half Canada’s total. It is also Canada’s industrial heartland, and US tariffs could devastate the economy.