When Andrés Manuel López Obrador triumphed one year ago, it was unclear whether Mexico had elected the revolutionary populist from the campaign trail, or the more pragmatic figure from his tenure as mayor of Mexico City. We may now have the answer.

The latest: Finance Minister Carlos Urzúa excoriated the leftist president on Tuesday, penning a resignation letter that accused him of failing to base policy on evidence and empowering ideologues over experts.

Between the lines: “Hope for pragmatism is fading,” says Shannon O’Neil of the Council on Foreign Relations. “These resignations show there's little hope for those who want change within the boundaries of checks and balances and democratic institutions.”

“After he lost two elections [in 2006 and 2012] he thought were stolen, I think that pragmatism went away,” she says.

"He did advertise this,” says Roberta Jacobson, who served as U.S. ambassador to Mexico from 2016-2018. “He's doing what he said he was going to do. He is the decider, he's not an institutionalist."

“Everything that blocks his decision-making has to be chucked over the side,” she adds, contending that the president’s efforts to undermine regulators and the civil service are leading to a "death of expertise."

“The tragic thing about López Obrador — and I’m still hoping he’ll succeed — is his diagnosis of the problems in Mexico was absolutely accurate. But his programs for fixing the problems are absolutely wrong."

Yes, but: While investors and experts are increasingly wary, López Obrador boasts approval ratings above 60% nationwide.

Everything is driven by the force of his personality, which is on display daily in early morning press conferences. Aides rarely speak, and he often contradicts them when they do.

But there’s one person López Obrador has scrupulously avoided confrontation with. On May 30, President Trump said he’d hit Mexico with tariffs that would escalate “until the Illegal Immigration problem is remedied.”

López Obrador immediately sought to defuse tensions, and eventually agreed to send 6,000 national guard members to the border with Guatemala, among other steps, to gain a reprieve.

The big picture: Jacobson says López Obrador told her he’d do everything possible to maintain a positive relationship with the U.S., “and he has continued to abide by that, almost beyond reason.”

Where things stand: Trump tweeted today that Mexico “is doing great at the Border.” But appeasing a president who regularly attacks your country, and could still reverse course with an election looming, is politically risky.

It’s also expensive. López Obrador didn’t get any financial assistance from the U.S. for the immigration offensive, O’Neil notes.

It’s just one case of his ambitious and costly plans running up against fiscal reality. And while his base of 25-30% will stand by him indefinitely, the rest of the country won’t be so patient, O’Neil says.

"He's going to face an economic and fiscal crisis and that's when I think that other 25-30% might go away."

What to watch: Jacobson agrees that “a train-wreck may be coming." She says we might find out then whether López Obrador has retained his pragmatic streak.