MEXICO CITY (Reuters) - U.S. Ambassador to Mexico Roberta Jacobson will step down from the job in May, she said on Thursday, joining a growing list of senior State Department officials to resign from the agency during the presidency of Donald Trump.

FILE PHOTO: U.S. Ambassador to Mexico Roberta S. Jacobson raises her glass in a toast as she attends a ceremony to place the first stone of the new U.S. Embassy in Mexico City, Mexico February 13, 2018. REUTERS/Edgard Garrido/File Photo

Jacobson’s decision comes as relations between the two neighboring nations are at a low point, thanks to Trump’s threats to abandon the North American Free Trade Agreement (NAFTA) and force Mexico to pay for a border wall.

“After 31 years of serving the U.S. government, I will leave at the beginning of May in search of new opportunities. I leave knowing that the U.S.-Mexico relation is strong and crucial,” she wrote in a statement on Twitter. “Together we are stronger!”

Jacobson added that she did not know who would replace her.

The U.S. Embassy in Mexico City referred questions about Jacobson’s resignation to her Twitter statement.

Earlier on Thursday, Mexican newspaper Reforma reported that Trump plans to nominate former AT&T Chief Executive Ed Whitacre as the next ambassador to Mexico.

U.S Secretary of State Rex Tillerson told his Mexican counterpart, Foreign Minister Luis Videgaray, in a February 17 phone call that Jacobson had resigned, the foreign ministry said in a statement.

“It is exclusively the job of the U.S. government to reveal publicly who it will name to lead its diplomatic representation in Mexico,” the foreign ministry statement said, thanking Jacobson for her service in Mexico and across the region, and wishing her well in future endeavors.

Appointed by former President Barack Obama, Jacobson became ambassador to Mexico in May 2016, after serving as the State Department’s Assistant Secretary of State for Western Hemisphere Affairs.

Many expected Trump to quickly ditch Jacobson due to her links to the Obama administration, and her often-vocal differences with some of the U.S. president’s declarations, such as his proposed border wall.

Since Trump took office, she has increasingly been viewed as a lame duck, with Mexican diplomats choosing to channel U.S. foreign policy through White House advisors, and particularly his son-in-law, Jared Kushner.

Nonetheless, Mexican diplomats say she was well-regarded.

Last month, the State Department’s third-ranking official, Tom Shannon, announced he was stepping down.

The departures of Shannon, Jacobson and William Brownfield, the former U.S. assistant secretary for International Narcotics and Law Enforcement Affairs, deprive the U.S. diplomatic service of many of its most experienced Latin American experts, during a crucial election year in the region.

They are part of a steady stream of senior career diplomats who have left since Trump became president.