As the US tries to wrap up its overhaul of the North American Free Trade Agreement, it wants to add new rules that would penalize the Mexican auto industry unless it boosts wages to about $16 an hour. This could be negotiators' final chance to reach a deal before the talks are put on hold during upcoming elections.

The proposed new rules could be a challenge for Mexico, where the Ann Arbor, Michigan-based Center for Automotive Research has estimated auto assembly workers on average earn under $6 an hour, and workers at auto parts plants on average earn less than $3 an hour.

Experts claim that any deal rests on the ability of Mexico and the United States to resolve the dispute over auto parts. If an agreement is not reached this week, it is improbable that NAFTA will be revised this year, as both Mexico and the US will soon be occupied with national election campaigns through the remainder of 2018. Mexico has an upcoming presidential election and the US has midterm congressional elections.

Other challenges include the future of the pact's dispute-resolution mechanism and a US proposal for a sunset clause that could automatically kill the deal after five years.

"We will be working all week on this," Mexican Economy Minister Ildefonso Guajardo told reporters after talks with US Trade Representative Robert Lighthizer. Asked how long he would be staying in Washington, he replied: "We will be here for as long as necessary."

Guajardo earlier told the news that if a deal could not be reached, "we would be operating what some analysts have called 'Zombie NAFTA' ... (one) that isn't dead and isn't modernized."

The classification of the NAFTA as a "zombie" endeavor is nothing new; there have been contentions against its productivity on all fronts for years now.

Mexico's main auto sector lobby have criticized the latest US demands, which also include raising the North American content to 75% from the current 62.5% over a period of four years for light vehicles, calling them "not acceptable."

Despite claiming that he wants to secure a deal in the coming weeks, Secretary Lighthizer has failed to display signs of softening on proposals that Canada and Mexico see as damaging to their interests, particularly concerning the automotive industry.

Lighthizer said last week that if the talks took too long, approval by the Republican-controlled US Congress may be on "thin ice." The aim is to complete a vote during the "lame-duck" period before a new Congress is seated after November's congressional elections.

"What the U.S. government seeks is not to modernize the old NAFTA but rather to get an agreement that would destroy trade and investment among the three North American partners," former Mexican president Ernesto Zedillo wrote.

Sealing the deal before elections implies that 95% of the deal will have to be agreed to. Whether this is feasible or not will depend entirely on the American disposition and willingness to concede to some extent. Thus far, the US has shown little inclination to capitulate.

Lighthizer has raised the idea of a quick agreement in principle to cover the general outlines of a text, leaving officials to work out the exact details later.