MEXICO CITY (AP) — Mexico’s top diplomat, Alicia Bárcena, said Friday that President Andrés Manuel López Obrador wants to travel to Washington D.C. in early November to meet with U.S. President Joe Biden about immigration, development aid and drug trafficking.

The statement comes after a surge in migrants moving through Mexico forced the closure of some U.S.-Mexico border crossings and led Mexico’s largest railway company to halt about 60 train runs because so many migrants were hopping aboard freight cars. Most appear to be Venezuelans, and many said they had crossed through the jungle-clad Darien Gap that connects Colombia and Panama.

Bárcena told a news conference in New York that migrant shelters in Ciudad Juarez, across from El Paso, Texas, are 95% full and that the Mexican government is “very worried” about the border closures and the migrant surge, especially given Mexico’s rocky relationship with Texas Gov. Greg Abbott.

In the past, Abbott has tightened border truck inspections and strung a series of floating barriers in the Rio Grande to try to deter migrants.

Bárcena suggested that more should be done to stem the flow of migrants through the Darien Gap, and that lifting U.S. economic sanctions against Venezuela “could also help us return some people to their home countries.”

There were signs that some in Mexico, too, were getting overwhelmed by the surge in migrants.

Bárcena said about 140,000 migrants were waiting to register for transit or asylum papers in the southern Mexican city of Tapachula, near the border with Guatemala, adding “we need reinforcements, because it is impossible to process 140,000 people.”

And early Friday, a few dozen residents who live near an overcrowded migrant shelter in Mexico City briefly blocked traffic on one of the city’s main expressways, saying migrants living in the streets outside the shelter were causing problems.

Mexico is also where most of the synthetic opioid fentanyl is produced for the U.S. market, using precursor chemicals smuggled in from China.

Bárcena’s comments came just a day after López Obrador announced he will skip the Asia-Pacific Economic Cooperation summit in November in San Francisco because his country “has no relations” with Peru.

López Obrador previously claimed Peru’s current government was installed by a coup and that he still considers ousted president Pedro Castillo to be the country’s legitimate leader.

Both countries recalled their ambassadors following those comments.

It would not be the first time that López Obrador has skipped international meetings in the United States because of who else was or wasn’t invited. Last year, he skipped the Summit of the Americas in Los Angeles because Nicaragua and Venezuela were not invited.