"We're in a political season now and it's always difficult to get things done," Obama said at a town hall meeting in Laos. "So after the election, I think people can refocus attention on why this is so important." He sounded confident: "I believe that we'll get it done."

The latest salvo from opponents of the deal came in the form of a letter to Congress signed by hundreds of law professors and economists – including Laurence Tribe, who taught Obama at Harvard – protesting the inclusion of "Investor State Dispute Settlement" (ISDS) provisions in the TPP agreement.

The ISDS provisions would empower corporations who object to U.S. laws and regulations that cut into their profits to sue the United States before an international arbitration panel.