By John S. McClenahen Even if the U.S. Senate this week approves trade promotion authority (TPA) the much-sought-after measure may still not be within the White House's grasp. That's because the U.S. Congress' upper house is expected to pass legislation containing a health-insurance provision for displaced workers that was not included in the TPA measure the House of Representatives backed by one vote last Dec. 6. Before legislation would be ready for President Bush's signature, differences between the two versions would have to be worked out in a conference committee, and both houses would have to approve the new version. Presidents from Ford to Clinton had what was then called fast-track authority for all of part of their terms. But it lapsed in 1994 and so far has not been renewed. TPA would allow Congress to approve or reject trade deals that the White House cuts with foreign countries -- but would not allow legislators to second-guess the President through amendments. The Bush White House has argued that other countries will not seriously negotiate with the U.S. on a new round of world trade talks or a free-trade area for the Americas until the President gains TPA.