U.S. Customs and Border Protection Acting Commissioner John Sanders attends a Police Week event in Washington, U.S. May 16, 2019. He did not give a reason for leaving his job.
"Although I will leave it to you to determine whether I was successful, I can unequivocally say that helping support the unbelievable men and women of his CBP has been the most fulfilling and satisfying opportunity of my career", Sanders said in a statement.
In an interview last week, Sanders blamed the problems in detention on a lack of money.
Democrats in the House of Representatives have been trying to push through a $US4.5 billion bill ($NZ6.7b) in emergency aid for the border, but the issue has divided liberals, particularly those in the Hispanic and Progressive Caucuses.
At the White House Trump said he did not ask Sanders to resign, adding that he doesn't think he has ever spoken to the man.
Morgan previously led the U.S. Border Patrol, a subsidiary of CBP, under President Barack Obama.
Meanwhile authorities in Texas reported seven migrant deaths yesterday, including those of a woman, two babies and a toddler, showing the danger of extreme summer heat as Central American families surge across the US-Mexico border. Several youngsters had the flu.
He was one of many others who felt repulsed that they couldn't help provide a shower or towel for those in need at the border after an attorney for the U.S. Department of Justice argued in court last week that the government shouldn't have to provide the basic sanitary products.
CBP officials and lawyers who have visited Border Patrol stations in recent weeks have said hundreds of children are in concrete Border Patrol cells without the specialised care they are afforded under the law because the agency tasked with providing it has run out of space.
Sanders has held the post for just over two months, after President Trump tapped his predecessor, Kevin McAleenan, to be acting chief of Homeland Security.
His appointment comes as the top leadership of most us immigration agencies remains in upheaval.
Customs and Border Protection commissioner John Sanders did not specifically mention the deteriorating conditions at border camps in his resignation letter, writing that he encouraged "everyone to reflect on all that you have accomplished as a team".
More than 52,000 unaccompanied children have been moved from the Department of Homeland Security to HHS, as of June 10. The lawyers negotiated access to the facility with officials, and say Border Patrol knew the dates of their visit three weeks in advance. It recorded 84,500 apprehensions of adults and children traveling together in May.
Government facilities are overcrowded and five immigrant children have died since late past year after being detained by Customs and Border Protection.
But Clara Long, an attorney who interviewed children at Border Patrol Station 1 last week, said conditions were not necessarily better there. These children usually remain in HHS custody until a sponsor is found for them.
The infants and children were housed at the center in Clinton, about 25 miles southeast of El Paso.
But Border Patrol agents have not allowed locals to help those who have been held according to Austin Savage and his five friends, who crammed an SUV full of $340 worth of purchases from a Target in El Paso which they tried to donate.