A meeting between U.S. President Donald Trump and Chinese President Xi Jinping to sign a long-awaited interim trade deal could be delayed until December as discussions continue over terms and venue, a senior official of the Trump administration told Reuters on Wednesday.

The official, who spoke on condition of anonymity, said it was still possible the “phase one” agreement aimed at ending a damaging trade war would not be reached, but a deal was more likely than not.

Dozens of venues have been suggested for the meeting, which had originally been scheduled to take place on the sidelines of a now-canceled mid-November summit of Asia-Pacific leaders in Chile, the official said.

One possible location is London, where the two leaders could meet after a NATO summit that Trump is due to attend from Dec. 3-4, the official said. “It’s under consideration but nothing decided,” the official said.

Other sites are possible in Europe and Asia, but the former is more likely, with Sweden and Switzerland among the possibilities. Iowa, which Trump has suggested, appeared to have been ruled out, the official said.