The value of China’s yuan hasn’t appreciated enough against the U.S. dollar and American manufacturers are bearing the brunt of currency manipulation, Ohio Democrat Sen. Sherrod Brown said Tuesday, a day ahead of the start of meetings between high-level U.S. and Chinese officials.

“It means basically a tariff on our exports to China, and it means a subsidy to Chinese imports here , Chinese exports to the U.S.,” said Brown, author of a bill that would allow the U.S. to slap duties on Chinese goods entering the U.S. if the Treasury Department finds that the currencies are misaligned. In a letter to Treasury Secretary Jacob Lew and Secretary of State John Kerry, Brown said the pair should press Chinese officials to end intervention in currency markets.

The Treasury Department has repeatedly declined to name China a currency manipulator, most recently in April.