European Trade Commissioner Peter Mandelson has said he has become more optimistic that an agreement can be reached in the World Trade Organisation talks.
Trade ministers are due to meet in Geneva next week, and that meeting could pave the way for a final deal later this year.
Next week's meeting is supposed to reach agreement on modalities - the framework in which a detailed WTO deal will be worked out in the late autumn.
The EU is expected to open its market more to developing world agriculture in return for developing countries opening up access to the market in industrial goods and services.
But there is still strong resistance to the deal among Irish farmers.
Irish Farmers Association President Padraig Walshe said only an Irish veto and strong French resistance can now stop Peter Mandelson's 'sell-out' of European agriculture.
Padraig Walshe told Agriculture Minister Brendan Smith at a meeting this evening that the time has now come for the Government to declare publicly its intention to veto the deal on the table.
Otherwise, Mr Mandelson will simply push ahead, he said.
Mr Walshe said a WTO deal would cost the Irish economy €4bn in losses each year. 50,000 farmers would be put out of business and 50,000 jobs would be lost in food processing and agricultural services.
'Beef prices would fall to €2/kg (70p/lb), making production unviable in this country and the slaughter of our suckler herd of 1m cows,' Mr Walshe said.
'Dairy prices would fall to an unsustainable 24c/l. The sheep industry would be decimated by imports from New Zealand and Australia,' he added.
