A proposed tax on imports that President Donald Trump is said to be warming to could upend the competitive landscape for carmakers, boosting Ford Motor Co. while hindering manufacturers that rely more on overseas factories, including Toyota Motor Corp.

House Republican leaders have proposed a so-called border-adjusted tax, which would place a levy on vehicles imported into the U.S. and fully exempt those exported. Though Trump initially deemed the idea too complicated, White House Press Secretary Sean Spicer last week said it was under consideration and could help pay for a wall along the Mexico border.

The overhaul to the U.S. tax system could hand an advantage to Ford, Honda Motor Co. and General Motors Co., which rely the least on imported vehicles among major automakers. The shake-up would also undermine Toyota, which relies on shipments of RAV4 sport utility vehicles from Canada and Lexus luxury models from Japan, and deliver an even more damaging blow to companies with zero domestic production, including Mazda Motor Corp.