Mexico’s first female president has stunning power. Can she use it?

Yet the 62-year-old engineer takes office amid a swirl of uncertainty. The economy is slowing, and Mexicans fear a budding cartel war in Sinaloa state. Relations with the United States have hit a rough patch.

The greatest source of unpredictability may be the Mexican political system itself.

Sheinbaum has built her political career as a loyal follower of outgoing president Andrés Manuel López Obrador — so loyal that she sometimes mimics his slow, pause-filled speaking style. But it’s unclear how closely she’ll follow his policies. López Obrador, a longtime icon of the left, delivered an idiosyncratic mix of nationalist energy projects, pragmatic deals with Washington and big spending on the poor. He’s concentrated power in the presidency and the military.

Morena is now so dominant that Mexicans are likening the new government to the one-party system that ruled for most of the 20th century. Under that system, presidents traditionally would serve their sole, six-year term allowed by the constitution, and then retire from politics. López Obrador, however, is leaving office with approval ratings north of 70 percent and showing every sign he plans to maintain his influence in the party he founded.

“The strongest president in recent history will begin her term as the most constrained,” the political scientist Jesús Silva Herzog Márquez wrote in the daily Reforma.

Mexico has relatively weak democratic institutions, and the political system often follows informal rules involving consultations between the presidency and different sectors of society. Now those rules are in flux. Sheinbaum, having trounced the opposition, won’t face the kinds of checks and balances that her predecessors did.

Nor is she likely to be held back by the courts. López Obrador, in his last weeks in office, rammed through a constitutional amendment to dismantle the judiciary. Going forward, Mexicans will elect nearly all their judges, including those on the Supreme Court. Legal scholars and diplomats warn that the system will produce a politicized judiciary.

Sheinbaum, who holds a PhD in energy engineering, has promised to continue many of López Obrador’s popular programs, such as cash benefits for the poor and working class, but to replace his freewheeling style with a more scientific approach. Supporters note her reliance on data to tackle crime and the coronavirus pandemic while she was Mexico City mayor.

But she’ll have to navigate a political system built around López Obrador. If there was any doubt about his intentions, it was settled in September when Morena elected his son, a shrewd political operative known as Andy, to a top party position.

Sheinbaum will inherit a complex financial picture. Mexico’s deficit is now nearly 6 percent of GDP, the highest since 1988, and Pemex, the state-run oil giant, is awash in debt.

Mexico became the No. 1 U.S. trade partner last year, but during López Obrador’s term, the economy grew less than under any president since the 1980s. There’s little sign of change in such slow growth; as the U.S. economy cools, Mexico is expected to follow. The central bank predicts GDP growth next year of only 1.2 percent.

Meanwhile, the peso has lost more than 10 percent of its value since Sheinbaum’s election, in part due to investors’ nervousness over Morena’s concentration of power.

“She has to send a clear message to investors, very, very fast,” said Gabriel Casillas, chief Latin America economist at Barclays. She will need to lay out plans to stanch Pemex’s losses and reduce the deficit, he said, as well as guarantee the independence of the central bank.

Sheinbaum, who has deep experience in global environmental issues, has said renewable energy “will be the hallmark of my government.” She’s promised to reduce Mexico’s dependence on fossil fuels and expand the production of sorely needed electricity. But analysts say she can reach her goals only by opening the energy sector to more foreign investment — an idea that’s been anathema to López Obrador.

The economy is only one of the urgent issues Sheinbaum will face.

In late July, Mexicans were stunned by news that two leaders of the Sinaloa cartel had been apprehended in New Mexico, after arriving in a private plane. One of them — Ismael “El Mayo” Zambada — later claimed he had been betrayed and kidnapped by the other, a son of drug kingpin Joaquín “El Chapo” Guzmán. Since then, their followers have traded attacks in Sinaloa state that have left more than 120 dead. Security analysts say the feud could spread.

More broadly, Sheinbaum faces a national security threat in the growing political and economic clout of organized crime groups. Many have moved beyond drug trafficking into large-scale oil theft, extortion, migrant-smuggling and other activities.

During López Obrador’s government, “a lot of groups have gotten a stronger hold over populations, politics and illicit economies,” said Falko Ernst, senior Mexico analyst for the International Crisis Group. “If you took away drugs right now, it wouldn’t necessarily resolve the conflict. They have all kinds of illicit economies to draw from.”

Sheinbaum is more cerebral and less folksy than the charismatic president, who hails from rural southern Mexico. She grew up in a Jewish intellectual family in Mexico City, and followed her parents into political activism on the left. She has signaled she’ll take a less polarizing, more inclusive approach than the pugilistic López Obrador, who bashed academics, journalists and other critics in his daily news conferences.

Sheinbaum has vowed to work productively with whoever wins the U.S. presidential election in November. But she takes office at a bumpy time in the bilateral relationship.

U.S. Ambassador Ken Salazar incurred López Obrador’s wrath in August by warning publicly that his judicial transformation posed “a major risk” to Mexican democracy and a threat to investment. The Mexican leader responded by declaring a “pause” in relations with the U.S. Embassy here. (He maintained ties with Washington.)

Sen. Chris Murphy (D-Conn.), who was part of the Biden administration delegation to the inauguration, said the U.S. government has expressed concern about the judicial change “because we want companies to feel 100 percent confident about leaving China and moving to Mexico.”

Mexico’s manufacturing sector stands to receive significant investment as American firms “near-shore” their production to be closer to U.S. markets, he said. “Right now the world should be Mexico’s oyster,” he said.

The United States has become increasingly dependent on Mexico’s government to restrain migration to the border. Washington has also leaned hard on Mexico to crack down on the flow of the deadly opioid fentanyl.

Sheinbaum has indicated she’ll continue López Obrador’s cooperative, pragmatic relationship with the United States. But that could be tested if former president Donald Trump, the Republican candidate, wins. He has promised mass deportations of undocumented immigrants, and floated the idea of a naval blockade aimed at Mexican drug cartels.

“The relationship with Mexico will be fundamentally different depending on what happens in the American elections,” said Murphy.

Valentina Muñoz Castillo contributed to this report.