Officials from the United States and the European Union say they have made progress as they seek to sweep away trade barriers. Teams from the two sides have held a week of discussions in Chevy Chase, Maryland. If successful an agreement would create the world's biggest free trade zone.
The chief US negotiator Dan Mullaney said the ultimate goal is to create opportunities for job creating trade and investment.
They are trying to do that by eliminating tariffs (taxes on imported goods) and removing what Mr Mullaney called non-tariff obstacles. This was the seventh formal round in an exercise that began last year.
Mr Mullaney said they have progressed from discussing general approaches to the spadework of reviewing the many proposals that each side has put on the table.
The planned agreement is known as the Trans-Atlantic Trade and Investment Partnership or TTIP. At a closing press conference, the chief negotiators from the two sides declined to give a timetable for finishing the exercise, insisting that it's important to get it right.
But while trade officials get on with detail, some of the general principles continue to generate vocal opposition.
Perhaps the most controversial area is the provision for foreign investors to go to an international tribunal for compensation if a government breaks the rules in a way that harms the company's interests.
The EU has held a public consultation on the provision and is currently analyzing the responses.
The Chief European negotiator, Ignacio Garcia Bercero said there was no discussion of that during the latest talks. The opposition to this idea has been taken up by the German government, so it remains uncertain whether it would appear in any final agreement.
Other critics are concerned that an agreement will drive down standards of consumer protection and food safety and will cost jobs. They also complain that the texts that negotiators are working on are not made public.
Polly Jones of the World Development Movement says: until there is public scrutiny of the negotiating texts, we do not know what standards are being lowered.
Director of War on Want, John Hilary, argues that TTIP undermines democracy.
He says some of the provisions would result in government regulations effectively being subject to a vetting process by private business, if the plans to enable companies to sue governments and for business representatives to sit on regulatory bodies go ahead.