US President Donald Trump has been the world's worst headache for the past 18 months, and arguably no country has suffered more than Mexico. Of the three main contenders in Mexico's just-completed presidential election, none was as ill-prepared as the winner, Andres Manuel Lopez Obrador -- Amlo, as he is known -- to manage the bully in the White House. Nonetheless, the Mexican people have chosen him, and he will have to deal with Mr Trump for much (if not all) of his six years in office.
Mexico's relations with the US were not a central campaign topic, nor will they figure among Mr Lopez Obrador's priorities. But they will surely affect Mexicans more than most other issues.
There are similarities between Mr Lopez Obrador and Mr Trump. Both appear to be sincere economic nationalists: Mr Trump hopes to make the US self-sufficient in aluminum and steel, while Mr Lopez Obrador seeks the same for Mexico in corn, wheat, beef, pork, and lumber. Both disapprove of trade treaties, although they temper their aversion with pragmatic selectivity: Mr Trump left the Trans-Pacific Partnership, but not the North American Free Trade Agreement (Nafta), while Mr Lopez Obrador says he will continue to re-negotiate Nafta with the US and Canada along the lines pursued by the current president, Enrique Pena Nieto.
Each man profoundly dislikes the other's country and panders to their nationalist supporters, who occasionally take their deep-rooted passions to extremes. But both know that they must negotiate, accommodate, and conciliate on-the-ground realities.
Despite these resemblances, Mr Trump and Mr Lopez Obrador are almost certain to plunge US-Mexican relations to new depths of suspicion and strain, as objective factors and subjective fervours aggravate old tensions and fuel new ones. Trade, immigration, drugs, security, and regional issues will continue to dominate the bilateral agenda, and on all these fronts, Mr Lopez Obrador will face the most adversarial US president in nearly a century.
On trade and tariffs, while Mr Lopez Obrador's specific stances are unknown, many of his economic proposals contradict the spirit of Nafta. Establishing floor prices for many agricultural products, and ensuring Mexico produces what it consumes, runs counter to many Nafta provisions -- and to Mr Trump's goal of reducing the bilateral US trade deficit.
Mr Lopez Obrador, who will take office on Dec 1, has pledged to uphold the treaty and continue talks to revise it. However, the changing of the guard will delay any final agreement and ratification by the three countries. In the meantime, Mr Trump's constant threats to withdraw from Nafta or impose new tariffs will inevitably irritate Mexico's new leaders.
Immigration will probably be an even touchier subject. Mr Trump's insistence on building a wall along the entire border, the rising number of Mexicans deported from the US heartland, Central American migrants crossing Mexico, separate detention of immigrant children, and Mr Trump's diplomatic and rhetorical pressure on all these fronts will not make things easier. Mr Pena Nieto's kowtowing to the US on most of these matters, ever since he invited then-candidate Mr Trump to Mexico City at the height of the presidential campaign, will logically lead Mr Lopez Obrador to distinguish himself as much as possible by standing up to Mr Trump as often as he can.
Mr Pena Nieto warned that he would use immigration and security as bargaining chips in pursuit of a holistic approach to all issues on the bilateral agenda. He never did. Once Mr Lopez Obrador moves beyond his simplistic views and understands the complexity of the issues involved, he will be tempted to do what Mr Pena Nieto dared not. Mexico can use a number of tools on immigration, such as loosening controls on its southern border with Guatemala or refusing admission to deportees from the US unless American authorities can corroborate their Mexican nationality. With mid-term elections coming in November, and the 2020 presidential campaign just around the corner, Mr Trump will find it difficult to desist from stoking his supporters' nativist animus.
The war on drugs is at a similar crossroad. The opioid crisis in the US shows no sign of abating, and a significant share of the heroin and fentanyl it consumes comes from Mexico, directly or in transit. Conversely, a growing number of US states are legalising medical and/or recreational marijuana; Canada has done the same. While Mr Lopez Obrador is highly conservative on these matters and opposes any kind of legalisation, he will find it difficult to maintain previous levels of cooperation with the US on drug enforcement. The public's animosity toward Mr Trump and resentment of the covert, intrusive, and probably illegal nature of the collaboration instituted by his two predecessors will not easily allow it.
Mr Lopez Obrador has insinuated that he believes in some sort of amnesty for small-time marijuana and poppy growers, though not for kingpins. But the line between them is not always clear. The peasants in Guerrero cultivate amapola for the cartels, not for their own livelihood. And the US will not look kindly on any backtracking from previous Mexican presidents' commitments to continue waging war on drugs in Mexico.
There are other issues on the US-Mexican agenda, ranging from intelligence sharing and counter-terrorism to regional crises such as Venezuela, Nicaragua, and possibly Cuba. Mr Lopez Obrador will almost certainly maintain Mexican cooperation on the first set of issues, while retreating to Mexico's traditional and archaic anti-interventionist stance on regional diplomacy. But Mr Trump cares more about security than he does about Venezuelan President Nicolas Maduro or Nicaragua's Daniel Ortega, so a real rupture may be avoided.
The hunger for change in Mexico, and the outgoing administration's incompetence and loss of credibility, probably made Mr Lopez Obrador's victory inevitable. Now Mexicans will have to face the consequences of their choice, just as their country must face the consequences of the choice the US made in 2016. - PROJECT SYNDICATE
Jorge G Castañeda, former Foreign Minister of Mexico (2000-2003), is Professor of Politics and Latin American and Caribbean Studies at New York University.