Under the TPA, the President's trade negotiations must follow guidelines and negotiating objectives set by Congress. If the negotiations follow the negotiating objectives, the implementing bill may pass Congress on a majority vote instead of the typically required two-thirds majorities. Congress may not amend or filibuster the implementing bill. The TPA is the mechanism used by the U.S. government to pass the North American Free Trade Agreement as well as other congressional-executive agreements. It has been praised for allowing the government to negotiate trade deals which would otherwise have been impossible to complete. However, it has also been criticized for usurping congressional powers and for lacking transparency.