When Justin Trudeau announced the end of US steel and aluminium tariffs at a steel mill in Hamilton, Ontario on Friday, onlookers witnessed something they had not seen in weeks — the Canadian prime minister smiling.

“This is just pure good news for Canadians,” said a beaming Mr Trudeau, standing before coils of steel. “Families will know that their jobs are just a little more secure.”

The break in trade hostilities with the US comes at a crucial time for Mr Trudeau. Over the past three months, a series of controversies have rocked his government and left his Liberal party trailing the Conservatives in the polls with just five months to go until the federal election.