U.S., Canadian, and Mexican negotiators are cloistered in theCamino Real on the edge of Polanco in Mexico City, their sessionsextending late in the night as they prepare for the arrival ofministers for the next round of talks on the North American Free Trade Agreement(NAFTA).

To contrast with the crackling tension ending the earliermeetings in Montreal, the Mexicans hope to leverage the rapportbuilt between Mexican Commerce Secretary Ildefonso Guajardo andU.S. Trade Representative Robert Lighthizer and announce new commonground.

Yet even if negotiators overcome still-daunting differences,NAFTA may still hang. It won't necessarily be President Trump whokills a new accord; instead, the biggest threats may lie in issuesof timing and circumstance beyond any one leader's control.