U.S. President Donald Trump’s controversial 20 percent tax on imports from Mexico to pay for a border wall would come as a second gift in less than a week for Canada’s oil patch. The tax, which White House press secretary Sean Spicer characterized as “theoretical,” would apply to countries “like Mexico,” with which the U.S. has a trade deficit, he said in a briefing Thursday. That would seemingly exempt Canada. The U.S. ran a surplus of $11.9 billion with the northern neighbor in 2015. This would potentially be a boon for Canadian oil sands producers whose heavy crude competes with Mexican supplies in the U.S. refining market. The proposed tax comes three days after President Trump revived the proposed TransCanada Corp.’s Keystone XL project to build a new crude pipeline from Western Canada to the U.S. Trump’s proposal “would attract more Canadian crude because it would be cheaper,” Bart Melek, the head of global commodity strategy at TD Securities in Toronto, said by telephone. “It just makes Mexican oil more expensive by 20 percent so it gives Canada a comparative advantage.” Canada is the biggest foreign supplier of oil to the U.S. and Mexico is the fourth-largest, Energy Department data show. Mexico’s easy waterborne access to the U.S. Gulf Coast refining center means its heavy Mexican Maya crude has sold for roughly 20 percent more than similar Western Canadian Select over the past four years, data compiled by Bloomberg show. Tense Relations Spicer’s comments came as relations between the U.S. and its southern neighbors deteriorated after Mexican President Enrique Pena Nieto canceled a planned visit to the U.S. following Trump’s insistence that Mexico pay for a border wall between the two countries. To be sure, many U.S. refiners get Mexican crude under long-term contracts that can’t simply be canceled. Some contracts may include language that allows them to be reopened if there is a big change in external environment, but how a border tax would affect those contracts isn’t clear, Afolabi Ogunnaike, an analyst at Wood MacKenzie Ltd., said by phone from Houston. Canada sent 3.24 million barrels a day of oil to the U.S. in October, while Mexico sent 555,000, Energy Department data show. Other countries might also be affected. Saudi Arabia, the U.S. second-biggest foreign crude supplier, had a trade deficit with the U.S. in 2012 of $31 billion, based on the latest available data provided by the Office of the U.S. Trade Representative. Western Canadian Select crude priced in Alberta traded at $40.28 a barrel Thursday, while Mexican Maya sold in the U.S. for $46.50 a barrel, data compiled by Bloomberg show.