Meetings also took place at the office of the U.S. Trade Representative, where one official said most of the talks are coming along well.
"I'm hopeful that in the next several days we'll have a breakthrough", Lighthizer said in response to a question from U.S. President Donald Trump on how talks were progressing during a U.S. cabinet meeting at the White House.
But Trump said on Thursday, "I'm in no rush".
Robertson says he thinks the USA will eventually work to achieve an agreement between all three countries, because getting the needed approvals through Congress would be far more challenging, otherwise.
"Their tariffs are too high, their barriers are too strong, so we're not even talking to them right now". A breakthrough between Mexico and the United States could come soon, but NAFTA talks will remain a slow affair until US sticking points with Canada can be resolved.
"Hopefully we will be able to close up no later than the middle of the week", he said.
Donald Trump is suggesting the United States has deliberately left Canada on the NAFTA sidelines as negotiations between Washington and Mexico have heated up in recent weeks. After the election, negotiations resumed without Canada and are seeking to tackle thorny bilateral issues such as revamped automotive sector rules and a sunset clause that could kill NAFTA after five years if it is not renegotiated.
There's still some hard issues to work on.
According to USA auto industry sources, the two sides are close to a deal to increase North American automotive content thresholds, with substantial requirements for content produced in high wage areas, namely the United States and Canada.
Guajardo said that the few remaining issues, mainly involving autos, are close to resolution, but Canada could be a fly in the ointment. This would protect the deal from the possibility of opposition if Democrats win control of the legislature.