A source close to the talks in Mexico City says a recurring pattern involves one country raising a prized priority only to have other parties refuse to engage the conversation.
But the source added that he remains hopeful a deal can be reached this year, and that obstinacy is to be expected in initial bargaining.
He cited two examples where Canada is digging in its heels -- its request for greater access to professional visas, and its refusal to discus the supply-management system with an eye to loosening Canada's import controls on American dairy and poultry.
Other sources say Canada wants the U-S to sign a series of international labour agreements it has yet to approve, and wants changes to labour laws in Mexico that would increase the salaries of auto workers.
A schedule obtained by The Canadian Press shows the 12 negotiating tables meeting today include the groups responsible for working on auto-parts rules, government procurement and Buy American rules, and intellectual property.