A group of sixty U.S. senators on Tuesday asked the Obama administration to consider the issue of currency manipulation as a part of major trade negotiations among Asia and Pacific nations.

Sens. Debbie Stabenow (D., Mich.) and Lindsey Graham (R., S.C.) circulated a letter among their colleagues urging Treasury Secretary Jacob Lew and U.S. Trade Representative Michael Froman to look into the issue of currency manipulation by other countries in the Trans-Pacific Partnership and future trade pacts. The letter to Messrs. Lew and Froman doesn’t include details of how alleged manipulation should be addressed.

“Currency manipulation can negate or greatly reduce the benefits of a free trade agreement and may have a devastating impact on American companies and workers,” the letter said.