Lange pointed to steel and aluminum tariffs, the threat of automotive duties, the long-running Boeing-Airbus disagreement, and a dispute involving Spanish olives as four major problems standing in the way of full cooperation.

He said the Europeans also feel that they have made a number of concessions since President Donald Trump and European Commission President Jean-Claude Juncker struck a trade truce in July 2018. He cited the EU's decisions to increase its soybean purchases and raise its import quota on hormone-free beef as two examples, adding that many European lawmakers do not feel they have seen the U.S. make similar gestures.

“How can I explain to make further concessions to the United States without any signal from the U.S. side?” Lange said.

Asked about the difficult issue of reducing barriers to agricultural trade, which the U.S. insists must be addressed in any negotiations, Lange reiterated the EU’s position that the topic was not a part of the limited mandate agreed upon during that July 2018 meeting.

“The appetite of the European side to negotiate is quite limited,” Lange said.

The current atmosphere is “totally different” from during the Transatlantic Trade and Investment Partnership talks — which lasted from 2013 to 2016 and included agriculture — because at that time “we had a comprehensive mandate and everything was on the agenda.”

Lange, however, noted that he was hopeful about the response he received on some trade topics. In meetings, USTR officials denied reports they were considering withdrawing from a procurement agreement at the World Trade Organization and were weighing whether to increase its bound tariff rates, he said.

But he cautioned that those positions could change "quickly."

"If you would ask me now, yeah, I got confirmation from all stakeholders that this would not happen," Lange continued. "I have no clue if you would ask me next week.”

A USTR spokesperson did not respond to a question about the U.S.' position on withdrawing from the Government Procurement Agreement. On the question of increasing its tariff ceilings, the spokesperson simply pointed to a previous statement acknowledging complaints with the WTO's set duty levels but saying there were "no plans at this time" to make changes.

Lange has been in Washington with a small group of European lawmakers to find ways to overcome trade disagreements and deescalate tensions. He said the group met with administration officials from the Office of the U.S. Trade Representative, the Commerce and State Departments, as well as members of Congress and the private sector.