The White House says President Obama would veto trade negotiation authority if it contains a provision that would punish countries that undervalue their currency.
Sen. Rob Portman, an Ohio Republican, and Sen. Debbie Stabenow, a Michigan Democrat, want the Senate to vote on an amendment to the trade bill that would place prohibitions on currency manipulation into trade agreements.
In a letter to key senators in the trade debate, Treasury Secretary Jack Lew says such a provision could be used against the United States if it uses monetary policy to protect the U.S. economy.
The Senate is debating so-called "fast track" trade authority that sets parameters for trade deals. Lew said he would urge Obama to veto it if currency provisions were added.