Andrés Manuel López Obrador is a seductive politician. From 2000 to 2005, he used to woo me, and the entire population of Mexico, at 6 a.m. every morning.

Mexico’s president-elect was then the mayor of Mexico City, arguably the country’s second most powerful post, and it gave him the perfect pulpit to show the rest of Mexico’s tired political class how to do politics.

A chief innovation was the 6 a.m. press conference. He held one every day without fail, long before the country was awake. The shtick was irresistible. Here he was, hard at work already, making himself available to the press before getting on with the people’s business.

It did the trick. Whatever the news, there was always a timely sound bite from the mayor on the first broadcasts of the day. Speaking practically and in simple words, he set the nation’s agenda. Pressed headline-writers started referring to him by his initials, AMLO, and it stuck.

Reporters at the morning pressers felt part of a special club and soon succumbed to AMLO’s charm. One news editor told me that he had to replace his reporter on the AMLO beat virtually every month, as they all became true believers.

It was clear that AMLO wanted to be president, that he had a great shot at winning the prize, and that Mexico’s establishment found this terrifying.

On Saturday, more than a decade after he stepped down as mayor, AMLO will finally receive the presidential sash. A wave of hostility from international investors has already greeted him. The peso has tanked to its weakest ever level, Mexican stocks are at their lowest in nine years, and ratings agencies have put the country on notice for a downgrade. Meanwhile investors greeted Brazil’s presidential choice of Jair Bolsonaro, a politician who uses neo-fascist rhetoric and has never held an executive position, with a rally.

The pessimism is overdone. At worst, it could be counterproductive and force AMLO into exactly the behavior that foreigners want him to avoid. Mexicans are used to feeling victimized by international capital markets, which at present see only the very good reasons for concern about AMLO, and not the reasons for hope.

After four years observing him as a reporter in Mexico City, here are the salient points I would offer about the man who was my mayor:

1. He is a pragmatist — you cannot survive more than five years running the biggest city in North America without being practical. Mexico City has many problems, but it was a cleaner, wealthier and safer place when he left than when he arrived.
2. He can make deals when needed. Notably, the revitalization of Mexico City’s glorious colonial historic center started as a partnership involving Carlos Slim, Mexico’s richest man; AMLO; and President Vicente Fox, a conservative. The mayor even hired Rudy Giuliani, his former New York City counterpart, as a consultant on crime.
3. He is a decent manager who inspires cult-like loyalty, but a poor delegator. His city offices were spartan, and he and those around him worked long hours. As mayor, he drove himself to work in a small car and gave himself a pay cut — an act he intends to repeat with civil servants. At the same time, there was corruption. His chief financial officer was caught on camera gambling for high stakes in a Las Vegas casino, for example, and subsequently served more than two years in prison for money-laundering. But no journalist has yet uncovered evidence that AMLO ever enriched himself.
4. He lacks imagination but not ingenuity. As mayor, he managed to manipulate budgets enough to set up “pensions” or welfare payments — which made him hugely popular.
5. Ideologically, he is a true believer. He has a clear-cut left-wing view of the world and regards such totems as the state control of Mexico’s national oil company, Pemex, to be beyond negotiation.
6. His populism can veer into absurdity. As mayor, he held referendums on such issues as whether the city should end daylight saving time. Sometimes the absurdity can look downright dangerous, as in his refusal to accept defeat in the presidential election of 2006, when he declared himself the “legitimate” president and camped out in a tent city in Mexico City’s main square. And, of course, in his decision last month to cancel construction of a new Mexico City airport on the basis of a thin “consultation” organized by his own party. He is also one of the least internationally curious men ever to run Mexico, and proudly admits that he does not speak English.
7. Most important of all, he is a seriously good politician, combining a Bill Clinton-caliber grasp of retail politics with a Ronald Reagan-caliber ability to appeal over the heads of Congress to the voters. This, as much as his left-wing ideology, is what scares the ruling elites. Mexico has suffered a long run of ineffective presidents, men who proved unable to overcome the cumbersome checks and balances in the constitution, and left office branded as failures. AMLO, with rare political talent and what looks like a workable majority in Congress, threatens at long last to get something done.

This is potentially positive. After decades of drift, Mexico desperately needs a clear direction. The risk, which is real, is that he will take Mexico emphatically in the wrong direction.

The president-elect’s handling of the airport, which had already raised bonds from international investors, was a dreadful signal to the rest of the world. But it looked more positive at home. The issue has been controversial for decades. Back in 2002, a plan for an airport on the same site was abandoned when the peasants who would have been displaced kidnapped the local mayor and held him at machete-point. Many Mexicans view the project as an unnecessary boondoggle, and we can hope that AMLO’s decision to dispose of it quickly earned him important political capital to use later.

AMLO still needs international capital, and he knows it. He also needs to run a workable budget, and the market sell-off has already sharply reduced his freedom of action. If things go badly, he is now perfectly placed to deploy the populist playbook and blame foreigners. A neighbouring power that’s firing tear gas over the border and calling Mexicans rapists will also help him to do this.

The market selloff has been an effective warning shot. For now, it behooves everyone in Mexico and beyond to give AMLO a guarded welcome, and the benefit of the doubt.​

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

John Authers is a senior editor for markets. Before Bloomberg, he spent 29 years with the Financial Times, where he was head of the Lex Column and chief markets commentator. He is the author of “The Fearful Rise of Markets” and other books.