Speaking at the 12th International Economic Forum of the Americas on Monday, he said that the main reason was that this particular round aims at a higher level of ambition than previous rounds, notably the Uruguay round.
"This Round is deeper, larger and fairer across the board," he said. "It therefore presents political complexities for all participants - and it will take some political courage to bridge the gaps that still remain among the key players."
Last minute negotiations at the World Trade Organisation's Hong Kong Ministerial in December which discussed the braking down of global trade barriers to agricultural products - resulted in an interim agreement that will mean negotiators have return to the bargaining table in 2006.
Since then, political courage has been in rather short supply, with the major players choosing to attack each other's commitments instead.
The EU trade commissioner recently called the US the 'biggest single block' to the successful completion of the round.
But Lamy remains confident that an effective resolution can be found.
"The level of reductions on subsidies and import tariffs which are already on the table double those of the previous round," he said.
"Developed countries are being asked to reduce their agriculture subsidies and open their markets to exports from other countries; some developing countries are being asked to reduce their import tariffs on industrial products both to developed as well as other developing countries.
"The end results should be impressive. For example, the highest agriculture tariffs will be down by 60 to 70 per cent, compared with a 36 per cent average during the Uruguay Round."
Lamy went on to say that the agriculture subsidies on offer are already twice what was accepted in the Uruguay Round.
"This round is fairer. In agriculture, specific flexibilities for developing countries will be available in the form of 'special products' and 'special safeguard mechanism'.
"There will also be flexibilities for developing countries to protect some sensitive sectors from industrial tariff cuts."
The CIAA has also called for a successful outcome to the current round of WTO talks.
"It is regrettable that negotiators missed the 30th of April deadline for drafting modalities," said Jean Martin, CIAA president. "But with the stepping up of the process during these last weeks until July, it is still possible to reach a conclusion on agriculture and other modalities by the summer."