People were losing jobs by the tens of thousands, they warned. Small and medium-size companies, which employ more than 70 percent of the Mexican work force, were running out of cash. The government needed to intervene, they argued. The data was irrefutable.

“I have other data,” shrugged the president, Andrés Manuel López Obrador, according to two businesspeople with direct knowledge of that conversation in April. “You do whatever you think you need to do, and I’ll do what I need to do.”

Across the globe, governments have rushed to pump cash into flailing economies, hoping to stave off the pandemic’s worst financial fallout.

They have mustered trillions of dollars for stimulus measures to keep companies afloat and employees on the payroll. The logic: When the pandemic finally passes, economies will not have to start from scratch to bounce back.

In Mexico, no such rescue effort has come. The pandemic could lead to an economic reckoning worse than anything Mexico has seen in perhaps a century. More jobs were lost in April than were created in all of 2019. A recent report by a government agency said as many as 10 million people could fall into poverty this year.

Yet most economists estimate that Mexico will increase spending only slightly — by less than 1 percent of its economy — a small amount compared with many large nations.

The reason? Critics and supporters agree: Mr. López Obrador.

Hostile toward bailouts, loath to take on public debt and deeply mistrustful of most business leaders, Mexico’s president has opted largely to sit tight despite what is expected to be widespread pain up and down the economic ladder.

“The government should help the private sector as much as it can, otherwise our gross domestic product could drop as much as 10 percent, which would be a disaster,” said Carlos M. Urzúa, a former minister of finance under Mr. López Obrador.