Canada and Japan will not wrap up negotiations for the 12-nation Trans Pacific Partnership unless the United States can guarantee that Congress will not try to re-write the deal, says Reuters. Officials from six TPP countries told the news agency that negotiations were clouded by uncertainty over the U.S. position. One source said Canada and Japan were waiting for Congress to approve so-called Trade Promotion Authority, which requires lawmakers to call a prompt vote on trade pacts and which forbids amendments. At the start of the year, U.S. trade officials said TPP was in the final stages of discussion but the conclusion of the talks has yet to be announced. The leaders of the Senate Finance Committee, which oversees trade, disagree over provisions of a trade-promotion bill.