U.S. lawmakers reached a compromise on rules that threatened to derail a proposed Pacific trade partnership by agreeing to soften tough provisions against human trafficking. An amendment to legislation allowing trade deals a rapid run through Congress had been dubbed a "poison pill" for the 12-nation Trans-Pacific Partnership, a key part of the administration's outreach to Asia. A bill before the Senate would bar countries deemed soft on human trafficking from trade deals with expedited treatment, potentially hitting TPP partner Malaysia, which appears on a U.S. blacklist, and disqualifying the whole deal. Malaysia and Thailand are on the list for failing to meet minimum standards in fighting human trafficking. The countries are facing a crisis of Rohingya refugees smuggled out of Myanmar by traffickers on crammed boats headed to their shores. New language offers an escape hatch for countries taking concrete steps to combat human trafficking, based on a certification from the State department. Democratic Senator Robert Menendez, who designed the amendment, said it would for the first time impose real consequences on countries "turning a blind-eye" to human trafficking. "Should this bill pass and be signed into law, at least we will not reward nations with the worst record on reining-in human traffickers with the benefits of a fast-track to American markets," he told the Senate. Menendez negotiated the changed wording with the top Democrat on the Senate Finance Committee, Ron Wyden. An Obama administration official welcomed a compromise. "This amendment will further encourage countries to take concrete actions to address human trafficking," the official said on condition of anonymity. Human rights groups expressed support for the proposed change, which is also backed by Republicans. "This approach strengthens U.S. leadership to prevent and end human trafficking around the world and protect the most vulnerable workers," said David Abramowitz, a vice president at Humanity United. Separate legislation cleared Congress to clamp down on human trafficking within the United States when the House of Representatives overwhelmingly backed the measure already approved by the Senate.