The new United States-Mexico-Canada Agreement (USMCA) is aimed at bringing more jobs into the United States, with Canada and Mexico accepting more restrictive commerce with the United States, their main export partner.
Even after the agreement is signed, however, it will face another series of hurdles before taking effect.
The USMCA will also need to be ratified by the legislatures of Canada and Mexico.
Dairy remains a sticking point, sources familiar with the matter said this week, noting the United States was demanding detailed information about Canada's protected dairy market.
Major U.S. industries and agricultural interests are also unhappy that the president has not yet removed tariffs on steel and aluminum imports from Mexico and Canada, as administration officials promised during the final stages of the three-way negotiations.
A particular sore point for the Canadian prime minister are the United States tariffs on steel and aluminium imposed earlier this year and he said these should be removed. Canada has said it will lift its tariffs once the US lifts its own. Mexico swiftly retaliated with import tariffs on some United States goods, including steel, apples and pork. -This follows the President's announcement in October that a deal had been reached.
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"A vast number of technical details need to be scrubbed and wrapped up", she added.
The Friday deadline is important as new Mexican President Andres Manuel Lopez Obrado is being swore into office on Saturday and he could scramble the hard-fought agreement between the three nations. 'The fact that this is an agreement in three languages adds to the level of technical complexity and it is on that level that we are just being sure that all the Is are dotted and all the Ts are crossed'.
When the three countries reached the deal at the end of September, Trump said he was not at all confident of obtaining congressional approval.
Outgoing Mexican President Enrique Pena Nieto is attending the G20 meeting.
Trudeau and Trump discussed their plans for the G20 summit in a November 27 phone call, according to the White House.
Mr Trudeau added that "the benefits of free trade must be broadly and fairly shared", before criticising USA tariffs on steel and aluminium. 'The two leaders discussed their disappointment in the announced closures of General Motors plants in their respective countries and their plans for the upcoming G20 Summit'.
The leaders of U.S., Canada and Mexico signed a new trade deal Friday to replace the long-standing North American Free Trade Agreement, but tensions remain over lingering steel and aluminum tariffs.