WASHINGTON — Acting Customs and Border Protection Commissioner John Sanders told employees Tuesday that he would be stepping down from his post July 5, according to a spokesman for the agency.

The resignation of Sanders, who became acting commissioner just two months ago, follows reports of children living in squalor at border stations where they often lack child care, bedding or even basic hygiene items.

In a letter to employees, Sanders said that he had offered his resignation to acting Department of Homeland Security Secretary Kevin McAleenan on Monday. Sanders did not give a reason for his departure, but thanked the employees for their service and said, "I will leave it to you to determine whether I was successful" as acting commissioner.

Acting ICE Director Mark Morgan is the favorite to replace Sanders, though this is not yet locked in, according to two administration officials.

Morgan, they said, is in good standing with the White House after being ready to carry out the mass deportations that wound up being canceled last weekend. He has previously served at CBP before going to ICE and began his career with the FBI.

Sanders was named acting commissioner after upheaval at the DHS led to the firing of its secretary, Kirstjen Nielsen, in April and then CBP Commissioner McAleenan took over the department in an acting role. CBP is part of the DHS.

Sanders previously served as CBP’s chief operating officer. Before coming to the agency, he was the deputy assistant administrator at the Transportation Security Administration. Sanders, like McAleenan, has been pleading with Congress to pass a $4.5 billion supplemental funding request to expand detention space, blaming the poor conditions for children on a backlog.

Sanders was also under pressure from the White House to crack down on the rising numbers of migrants crossing the border. In May, more than 140,000 undocumented immigrants crossed the U.S.-Mexico border, marking a 13-year monthly high.

Responding to public pressure, CBP moved roughly 300 migrant children out of the poor conditions in a border patrol station in Clint, Texas, to a tent detention camp in the El Paso area Monday. Roughly 30 remained at the Clint facility. CBP then transported a group of about 100 migrant children to the Clint site Tuesday because other facilities were stretched past capacity, according to a Border Patrol official.

It was not clear how many of the new arrivals were previously held at the Clint facility.