Under former President Donald Trump, US relations with its southern neighbour were quite simple: Mexico stopped the flow of Central American migrants from reaching the US-Mexico border and the two nations largely overlooked just about every other aspect of their bilateral relationship.

President Joe Biden, who took office almost two months ago, said he wants to change that dynamic, by reinstating a broader agenda with Mexico to include more engagement on climate change and security. He also promised to overturn the antagonistic legacy of his predecessor who called Mexican migrants rapists and said Mexico would pay for a border wall that would stop migrants from entering the US.

But Biden’s very different approach to US-Mexico relations may come into conflict with the interests of Andres Manuel Lopez Obrador, the left-wing Mexican president known by his initials AMLO, who was able to forge an unlikely working relationship with Trump.

“The Biden administration implies a very different environment for AMLO,” said Carlos Elizondo Mayer-Serra, author of the book, Y mi palabra es la ley: AMLO en Palacio Nacional (And my word is the law: AMLO in the National Palace).

“First, because there are deep differences in terms of what to do on climate change, and second because the relationship is going to be much more bureaucratically managed,” Elizondo tells Al Jazeera.

With career politician Biden in office, he said, diplomacy will be conducted through official channels, rather than by phone or Twitter – as was the case under Trump.

Despite being on opposite ends of the political spectrum, Trump and Lopez Obrador, observers have noted, are both populist leaders with a similar leadership style and visions about their respective countries. Apart from renegotiating the terms of the USMCA, the trilateral trade deal with Canada, neither saw strategic potential in partnership.

Reducing immigration into the US was a core issue for Trump. In 2019, amid a surge in Central American migrants arriving in caravans through the US-Mexico border, he threatened to impose tariffs on Mexico if they did not stop them.

Lopez Obrador relented. He abruptly switched from providing transport, shelter and transit visas to migrants headed north, to blocking their access using military force. The move won him favour with Trump and provoked little pushback at home.

Lopez Obrador was one of the last world leaders to congratulate Biden on his election win. And some tension between the two went on public display on March 1, in advance of their first bilateral meeting, held virtually.

With Mexico’s vaccination campaign off to a slow start amid a global scramble for more doses, AMLO said during a news conference before the meeting that he had asked the US to share its vaccine supply with Mexico. The US had a swift response.

“No,” White House Press Secretary Jen Psaki said in a news conference held a few hours later.

“The president has made clear that he is focused on ensuring that vaccines are accessible to every American,” Psaki said, “That is our focus.”

AMLO had also proposed a “Bracero-style” programme for 600,000 to 800,000 Mexican and Central Americans to work in the US. Psaki responded by saying that such a programme would require approval from Congress. A joint press release after the meeting made no mention of the proposal.

“I don’t think Biden is going to commit any political capital to a guest-worker programme,” said Tony Payan director of the Center for the United States and Mexico at the Baker Institute. “It’s absurd to believe that with the kind of unemployment rate – 11.5 percent in the United States – Biden would be willing to put that on the table,” Payan told Al Jazeera.

Al Jazeera