Friday's vote by the International Trade Commission was unanimous. The trade commission has until mid-November to recommend a remedy to President Donald Trump, with a final decision on tariffs expected in January.

White House spokeswoman Natalie Strom said Friday that Mr. Trump "will examine the facts and make a determination that reflects the best interests of the United States. The U.S. solar manufacturing sector contributes to our energy security and economic prosperity."

Georgia-based Suniva Inc., and Oregon-based SolarWorld Americas brought the case, saying a flood of imports have pushed them to the brink of extinction. Suniva declared bankruptcy, while SolarWorld had to lay off three-quarters of its workforce.

Cheap imports have led to a boom in the U.S. solar industry, where rooftop and other installations have surged tenfold since 2011.

The main trade group for the solar industry and many governors oppose tariffs, saying they could cause a sharp price hike that would lead to a drop in solar installations by more than 50 percent in two years.