The G8 negotiations in Northern Ireland could lead to the biggest trade deal in history, an upbeat David Cameron has claimed.
The Prime Minister said talks to break down trade barriers between the EU and the United States could create two million extra jobs and would help to “fire up” global economies.
They will commence next month in Washington and are scheduled to be completed by the end of next year — although they could take as much as two years if problems emerge.
Mr Cameron had sought to focus the gathering of world leaders on economic themes and was clearly elated about the chances of success for a “landmark deal”.
He described it as a “once in a generation prize” that he was determined to seize.
“The whole point of this meeting in Lough Erne is to fire up our economies and drive growth and prosperity around the world, to do things that make a real difference to people's lives,” he said.
Mr Cameron predicted that a successful outcome to the negotiations “could add as much as £100bn to the EU economy, £80bn to the US economy and as much as £85bn to the rest of the world. They mean extra jobs, more choice and lower prices in our shops”.
He added: “We are talking about what could be the biggest bilateral trade deal in history. A deal that will have a greater impact than all the other trade deals on the table put together.”
Mr Obama was equally enthusiastic about the potential benefits.
“America and Europe have done extraordinary things together before and I believe we can forge an economic alliance as strong as our diplomatic and security alliances, which of course have been the most powerful in history,” he said.
Mr Obama sounded a note of caution, however, predicting a bumpy right for the trade talks — although he insisted that he would intervene to help push them through.
And while a US-EU trade deal would be a “priority” for his administration, he warned against “downgrading ambition” in a rush to strike an agreement.
His caution may be explained because this was a success story that was pre-cooked, flagged up days before the G8 discussions even started.
It also marks the resumption of negotiations which have stalled in the past, not a final outcome.
Mr Obama said it was important that the US and EU “get it right”.
“That means resisting the temptation to downgrade our ambition or avoid tough issues just for the sake of getting a deal,” he said.
The President said the leaders would be giving a “mandate” to their negotiators, but added that it was likely they would have to step in personally to resolve particularly difficult issues.
Thrashing out the details of the agreement is expected to be challenging.
European Commission president Jose Manuel Barroso insisted “we intend to move forward fast”.
He said: “We can say neither of us will give up content for the sake of speed but we intend to make rapid progress.”
Mr Barroso said “huge benefits” were expected from reducing red tape between the two nations.
He added: “Integrating two of the most developed, most sophisticated and certainly the largest economies in the world can never be an easy task but we'll find convincing answers to legitimate concerns, we'll find solutions to thorny issues, we'll keep our eyes on the prize and we will succeed.”