The certification must hold that "in the 10-year period preceding the certification, the government … has not engaged in the intervention or manipulation of the rate of exchange between that country's currency and the United States dollar for purposes of preventing effective balance of payments adjustments or gaining unfair competitive advantage in international trade."

Snowe and several other members of Congress for years have been worried about the effect of currency manipulation on U.S. companies and U.S. exports. Much of this focus has been on China's currency, which even the U.S. Treasury Department finally acknowledged is "undervalued," although it did not go as far as saying China was purposefully manipulating its currency in order to gain a trade advantage.

The Snowe-Rockefeller bill would more immediately affect pending trade agreements with South Korea, Colombia and Panama. Republicans are hopeful that the Obama administration will soon send it implementing legislation on those agreements.

Nonetheless, Snowe said her legislation is driven in part by the experience with China.

"Manufacturers and workers in trade-sensitive industries, including Maine's paper production industry, have already been harmed by China's enduring mercantilist trade practices," she said. "This common-sense legislation will protect American jobs and competitiveness by ensuring that special trade privileges are not afforded to nations who engage in currency manipulation.

"It will also send a clear message to our potential free trade agreement partners that Congress and the president have a zero-tolerance policy when it comes to the unfair practice of currency manipulation," she added.