The U.S. International Trade Commission (ITC) announced Friday that its has unanimously determined that Chinese solar panel and cell imports are harming the American solar manufacturing industry.

That determination was one of the central questions the ITC was charged with answering in its ongoing investigation into allegations that China is illegally dumping its products into the American market. The ruling also means that the ITC and the Department of Commerce will proceed with their investigations that could ultimately lead to stiff tariffs on all solar panels and cells imported into the U.S. from China.

The U.S. Department of Commerce could rule as soon as Jan. 12 on preliminary tariffs and “critical circumstances,” which may mean importers of record would be required to pay duties on products received as far back as Oct. 14.

The dispute has deeply divided much of the solar industry. The Coalition for American Solar Manufacturing (CASM) lists 151 associate members on its website — many of which do direct business with SolarWorld. The Coalition for Affordable Solar Energy (CASE) represents 132 companies — many of which rely on panels coming in from China.

SolarWorld and CASM hailed the announcement as evidence that the trade complaint it brought forward with six other anonymous companies is based on current international trade law. “Today’s ruling further erodes the credibility of denials by Chinese manufacturers and their importer allies in this case,” said Gordon Brinser, president of Oregon-based SolarWorld Industries America Inc., in a written statement.

CASE co-founder Jigar Shah, meanwhile, urged leaders “to consider the impact of this proceeding on the entire American solar workforce and ask that it balances the needs of all American solar workers and the continued need for affordable solar energy. SolarWorld represents approximately 2 to 3 percent of the U.S. solar job market, whereas the other 97 to 98 percent of U.S. solar job market will be negatively impacted by this lawsuit."

Members of Congress also weighed in on the matter Friday, signifying its growing significance as a political issue. In a letter sent to President Obama, 59 legislators (six senators and 53 representatives) backed SolarWorld’s position. In their sweeping letter, the legislators, all Democrats, made the case that the investigation “comes at a critical juncture for the U.S. clean energy technology sector and underscores the need to ensure a level playing field for American businesses and workers.”