Brussels and Washington say a trade pact encompassing almost half the world's economy could generate $100 billion in additional economic output a year on both sides of the Atlantic, as well as creating a market of 800 million consumers.
But since talks were launched eight months ago, reports of U.S. spying in Europe and accusations that an accord would pander to big companies have combined to erode public support.
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Moscow's seizure of the Crimea region from Ukraine and Europe's reliance on Russian energy have focused minds across Europe about the need for stronger ties with the United States, while European Trade Commissioner Karel De Gucht warned that Russia was no longer a reliable partner.
"We should have a very clear idea of what Russia is doing by annexing Crimea. It doesn't have a place in normal international relations," De Gucht later told a conference alongside Froman.
"Do we have to swallow that? I think there is a price for that and I think we should be very clear, the EU and the United States together, that they (Russia) simply cannot do this," he said, although he declined to say if he backed a trade embargo.
Rethinking relations with Moscow
EU leaders dedicated a summit in Brussels on Thursday and Friday to rethinking relations with Moscow and accelerating their quest to reduce the bloc's reliance on Russian oil and gas, an area where the United States can play a role.
Froman laid out how companies could export U.S. liquefied natural gas (LNG) in tankers to Europe, as France, Germany and Britain seek, benefiting from the U.S. shale gas revolution.
Under U.S. rules, the Department of Energy must issue licenses to exporting companies, but license approval becomes much easier under a free-trade agreement, or FTA.
"Clearly, when the T-TIP is done, assuming it is done, there will be an FTA relationship with the European Union," he said.
Asia is for now a more lucrative export market for U.S. liquefied natural gas, but Froman said it was also up to European companies to decide where gas goes, and that exports did not depend on a transatlantic trade deal.
"Even right now, there have been four or five licenses approved for export to non-FTA countries. There are several European companies who are the contractors," he said, naming France's Total and GDF Suez.
"Where that gas goes is up to them. Conceivably, European governments have an interest in them bringing that gas to Europe," Froman said.