Negotiations on the ambitious Trans-Pacific Partnership were to go into overtime Friday as top trade officials from 12 countries strained to craft a deal that would create the world's largest free trade zone.
The talks remained bogged down after two days of negotiations between ministers from the United States, Japan, Australia and nine other countries over a handful of sticky issues.
Disagreements persisted over how the US opens its market to auto parts from Japanese car makers, and how much Canada is willing to open its market to dairy products from Australia and New Zealand like cheese.
Also still unresolved is the US push to establish lengthier patent protections for biologic drugs -- those made using living organisms.
Worries were that the negotiators would again be unable to bridge their differences on a project deeply important to the administration of President Barack Obama, two months after a meeting of the ministers in Hawaii failed to strike a deal.
The decision to hold a meeting of trade ministers on TPP so soon after Hawaii had been seen as a sign that they were very close to finalizing a deal.
Since initiating the talks in 2008, the United States has been hoping to lock in rules on free trade and intellectual property protection that global trade heavyweight China would eventually have to heed.
The 12 countries in the TPP discussions -- they also include Brunei, Chile, Malaysia, Mexico, Peru, Singapore, and Vietnam -- represent about 40 percent of the global economy, and so any agreement would lay down broad standards.
China, however, has already begun trying to set up its own Asia trade agreement, which analysts worry could take concrete shape if TPP talks fail.
There was no official news about how close the countries were to achieving agreement, but clearly officials were hoping that another day of talks could produce at least some real progress if not a final pact.
US Trade Representative Michael Froman, the host and one of the key driving forces behind the TPP talks, said that "everyone is working hard to find pragmatic solutions to the difficult outstanding issues."
But pressure was mounting from interest groups in various countries for them not to give away too much.
In a letter a group of senior US legislators reminded Froman that Congress's support is key to getting any final pact ratified.
"We urge you to take the time necessary to get the best deal possible for the United States, working closely with us and with stakeholders to resolve the many outstanding issues in these critically important negotiations," they said.
Meanwhile a group of Canadian provincial officials traveled to Atlanta to press Ottawa's negotiators to protect the country's dairy sector from an increase in imports from dairy powers Austria and New Zealand.
If a proposal is accepted to allow another 17,000 tonnes of foreign cheese into Canada, it will kill about 400 family farms in Quebec province, argued Pierre Paradis, the Quebec agriculture minister.
But Australian lobbyists said they would only accept an overall deal that opens more doors for their dairy products in Canada -- and that provides greater access to US markets for their sugar.
"We are an industry with no subsidies, we are free-traders," said Robert Pettit of the Dairy Australia industry group.