WASHINGTON — For companies like General Electric and Honeywell, it would help open untapped global markets, lift exports and create middle-class American jobs. For labor groups like the A.F.L.-C.I.O. and the Teamsters, it is a threat to American workers, bound to lead to lost jobs and lower wages, as well as rising corporate profits.

At issue is the so-called fast-track trade approval, a green light from Congress for the Obama administration to complete two sweeping trade deals, one with Pacific Rim countries and the other with Europe.

President Obama, supported by many Republicans and business groups, has asked for fast-track approval to ease the eventual passage of his trade deals, which he argues would provide a shot in the arm for the economy.

But he has run into staunch opposition from members of his own party, as well as labor and environmental groups. They fear a further loss of jobs to the forces of globalization and technological change and inadequate protections against environmental damage.