No clear majority has emerged so far among EU member states for a free-trade agreement between the EU and the United States, and both sides need to explain the benefits of such a deal, the EU's Health Commissioner has claimed in an interview.
German Chancellor Angela Merkel has otherwise urged the 28 nation bloc to speed up negotiations with the US on what would be the world's biggest trade deal.
But there is public opposition in Europe based on fears of weaker food and environmental standards.
"We have to take people's concerns seriously," the EU Commissioner for Health and Food Safety, Vytenis Andriukaitis, told German's Tagesspiegel, adding that the trade agreement ultimately needed to be ratified by all national parliaments.
"At the moment, I don't see a safe majority for this yet," he said in an interview published on Monday, adding that the European Commission had published some negotiating papers to improve transparency.
The EU has said the final wording would, however, remain confidential until an agreement was reached on the Transatlantic Trade and Investment Partnership (TTIP).
Negotiations for the TTIP were launched in July 2013 and officials are seeking a deal that goes well beyond trade to remove barriers to businesses. There is concern in Europe that US multinationals would use a proposed investment protection clause to bypass national laws in EU countries.
In Berlin, more than 25,000 people joined a rally against the TTIP and genetically-modified food over the weekend.