"We have worked well together with border crossings being way down", he said. The official wasn't authorized to speak publicly and spoke to AP on condition of anonymity. McAleenan also has two young daughters and a wife with whom he wants to spend more time.
Trump never officially nominated McAleenan, keeping him in an "acting" role, which is now commonplace for a president who said he prefers the "flexibility". He said he would strive to ensure a smooth transition.
Acting Department of Homeland Security Secretary Kevin McAleenan submitted his resignation to the White House on Friday, after serving in the post since April.
McAleenan has been more isolated in recent weeks after the departure of several top aides and close allies.
McAleenan had managed a massive border crisis that quieted down recently following crackdowns and policies restricting asylum that he helped enact.
Footage Released Showing Errol Spence's Horrific Crash That Ejected Him From Car
A champion boxer is recovering in a Dallas hospital, after surviving an absolutely horrific auto crash. Spence Jr's injuries are "not life threatening", said Tim Smith of promoter Premier Boxing Champions.
The 240,000-person department is tasked with election security and cybersecurity, disaster response and even the Secret Service.
Homeland Security has been the cabinet post with the highest turnover in the Trump administration at this point.
He was among those behind the administration's widely maligned practice of separating families at the border previous year, though McAleenan later said he regretted the policy because it lost the public trust. And he dramatically expanded a policy initiated under Nielsen that forced migrant families to wait in Mexico while their asylum claims were heard. He was vocal in declaring that the USA immigration system was at a breaking point earlier this year as a crush of Central American migrant families streamed to the border seeking asylum, and he has advocated for agreements with other countries that would shift the burden of accepting asylees away from the United States. McAleenan is not tied to that inquiry, spending the vast majority of his career in government has been focused on border security. McAleenan has held also held senior posts within Customs and Border Protection in President George W. Bush's administration.
In a New York Times report last month, McAleenan was accused of telling federal immigration officials to ignore Trump's orders at the U.S. -Mexico border.
McAleenan went before Congress to ask for more than $1 billion in emergency funding that eventually passed and some of the pressures eased; the last month of the budget year saw major declines in crossings.
His tenure played out against a backdrop of outrage amid reports of children being held in squalid conditions on the United States border and images of those who died trying to make the trek from Central America.