Canada and the U.S. are discussing a prospective deal in which Ottawa would tackle a list of Trump administration trade demands in exchange for Washington scrapping a threat to impose new tariffs, a source familiar with the talks said on Friday. Trump slapped tariffs on a range of Canadian imports after returning to power last year and in July unveiled 50% tariffs on a wide range of imports to take effect on August 19 unless Ottawa tackled U.S. grievances.