LOS ANGELES (CNN)  — The US ambassador to Mexico has announced that she is stepping down in May.

Roberta Jacobson made the announcement in a tweet in Spanish on Thursday, “I will be departing at the beginning of May, in search of other opportunities.”

READ MORE: Food Truck Crashes In Vernon; One Dead

The resignation comes at a time when US relations with Mexico have been strained over issues related to trade and migration and, Jacobson ended her tweet stating, “We are Stronger Together!”

“I do it knowing the US-Mexico relationship is strong and vital and that this amazing Mission Mexico team will continue to ensure it remains so,” she adds. “At this time, I have no news to share on my successor.”

A source close to Jacobson said, “it was a tough job and she is looking for new opportunities outside government after 31 years.”

Jacobson is an experienced US diplomat who was nominated to the position in 2015 by then-President Barack Obama and confirmed the following spring.

She was closely involved with the Obama administrations’ efforts to reopen diplomatic relations with Cuba in her previous role at the helm of the agency’s western hemisphere bureau as well as efforts to broker a peace deal between the Colombia government and the guerrilla group FARC.

Last weekend, Mexican President Enrique Peña Nieto called off an official trip to Washington to meet with President Donald Trump after a tense phone call.

CNN previously reported Peña Nieto was tentatively planning the trip for March, a White House official said, but the official confirmed that the trip was put on hold following the phone call, which took place on February 20.

State Department Spokeswoman Heather Nauert told reporters the agency is grateful for Jacobson’s service.

READ MORE: `Solidarity' Cited In New Deal For 40k Behind-the-Scenes Film & TV Workers

“She has certainly done a tremendous job in representing US interest with the government of Mexico,” said Nauert.

Jacobson is the latest in a series of high-ranking US diplomats to step down in recent months. Earlier this week, Ambassador Joseph Yun, the top diplomat in charge of North Korea policy, announced his resignation. In January, the US ambassador to Panama, John Feeley, also announced he would be stepping down.

In November, the head of the American Foreign Service Association, a union representing US diplomats, said the State Department’s senior tiers are being “depleted at a dizzying speed.”

“If you look at amount of time that many of these individuals have invested in their careers at the State Department … that’s a tremendous amount of time to be working in any industry, building, service, government agency, or department,” Nauert said, refuting the notion the department is experiencing a damaging loss of senior personnel. “People are choosing to retire for personal reasons, and that’s perfectly fine with us.”

Former Secretary of State John Kerry praised Jacobson on Twitter for her contributions to US foreign policy.

California Senate Leader Kevin de Leon issued the following statement Thursday
“Roberta Jacobson’s resignation as Ambassador to Mexico is a considerable loss for all Americans and an unfortunate setback for U.S.-Mexican relations. Ambassador Jacobson has served with distinction for over thirty years and is held in the utmost regard as a true expert in her field. Her departure is the latest in an exodus from the State Department that severely endangers America’s standing in the world.

Under Secretary Rex Tillerson, the State Department is a shadow of its former self. Our diplomatic corps already has an unprecedented number of vacancies in senior leadership posts around the world, and the President’s toxic behavior is straining even our strongest relationships.

Building walls and burning bridges only weakens America. We cannot afford to make enemies of our friends and neighbors, especially as we contend with very real threats to American interests and security abroad.”

MORE NEWS: Child, 18 Months, Killed in North Hills Crash

™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.