Negotiators have run into a series of early sticking points on nearly every major element considered key to achieving a new NAFTA agreement, The Canadian Press has learned.

A recurring pattern involves one country raising a prized priority only to have other parties systematically refuse to engage the conversation, said one source with knowledge of how the talks are unfolding in Mexico City.

"The tone is negative," said the source, who made sure to add that it's still early, he remains hopeful a deal can be reached this year, and that obstinacy is to be expected in initial bargaining.

This was excerpted from the 4 September 2017 edition of CBC News.