European Union trade ministers are meeting at Dublin Castle to try to agree on a mandate to start negotiations on a comprehensive free trade and investment deal with the US.
They will be joined by a senior US trade official and the head of the World Trade Organisation.
It is hoped the Transatlantic Trade and Investment Partnership will evolve into a free trade deal between the EU and the US.
The world's two biggest trading partners already trade €2 billion worth of goods and services across the Atlantic every day.
Both sides see potential gains to economic growth from a further liberalisation, mainly by scrapping technical barriers to trade that add cost and complexity to business in certain sectors.
European estimates say a comprehensive deal could boost EU output by half a percentage point of GDP, and add several hundred thousand jobs.
For the first time a senior US trade official - Deputy National Security Advisor for economic affairs Mike Froman - will attend part of the ministerial discussion.
Business leaders from Ireland, the EU and the US will also meet in the margins of the conference, at events organised by IBEC and the US embassy.