WASHINGTON—The Trump administration is casting the widest possible net in considering whether imported autos should be subject to tariffs based on national security grounds, worrying auto exporters from Mexico to Germany and generating complaints from Republican lawmakers.
The Commerce Department, which is directing the probe into whether a national security trade law should apply to imported autos, hasn’t ruled out the possibility that such tariffs would apply to countries such as Canada and Mexico, where the U.S. has a free-trade...