Kevin McAleenan, the acting secretary for the Department of Homeland Security, is out as the temporary chief of the department.

McAleenan, 48, is the fourth acting or confirmed secretary to have served atop the 240,000-person department since President Trump took office.

Trump announced his exit in a series of tweets Friday night, explaining that he "wants to spend more time with his family and go to the private sector."

....Congratulations Kevin, on a job well done! I will be announcing the new Acting Secretary next week. Many wonderful candidates! — Donald J. Trump (@realDonaldTrump) October 11, 2019

McAleenan also addressed his departure in a statement, thanking the president for the opportunity to serve the country and outlining the "tremendous progress" the department made during his time leading it.

I want to thank the President for the opportunity to serve alongside the men and women of the Department of Homeland Security. With his support, over the last 6 months, we have made tremendous progress mitigating the border security and humanitarian crisis we faced this year... pic.twitter.com/A4rTcZgJKF — Acting Sec. Kevin McAleenan (@DHSMcAleenan) October 12, 2019

Several sources told the Washington Examiner at the time of McAleenan’s appointment to DHS in April that Trump was testing him to see if he would be a good permanent fit and implement his agenda, due to his reputation within the department for opposing some of the White House’s immigration and border policies.

McAleenan’s household also for years gave solely to Democratic causes, including thousands to Hillary Clinton and Barack Obama, federal records show.

McAleenan is a lawyer and worked as a career employee at the department’s U.S. Customs and Border Protection agency for the better part of 15 years. He worked in CBP’s Office of Field Operations before being promoted in 2014 to the 60,000-person agency’s second-highest political appointee position as deputy commissioner.

McAleenan was named acting CBP commissioner in January 2017. He was officially nominated to be the permanent chief in May 2017 and confirmed 77-19 by the Senate in March 2018.

Trump promoted McAleenan in April when then-Secretary Kirstjen Nielsen left.

During McAleenan’s two years as the country’s top border official, the number of people arriving at the border grew from 16,000 per month to more than 144,000 per month. When he took over at Homeland Security this spring, he and the White House called for additional funding to address the surge. While Trump called for immediate fixes, McAleenan was focused on addressing root causes and coming up with bipartisan-supported solutions.

Democratic lawmakers complained CBP was not doing enough to care for those being taken into custody. DHS inspector general reports and media reports affirmed Democrats' claims.

Republicans claimed the “border crisis" was due to “loopholes” in old laws that were luring migrants. Lawmakers did not pass comprehensive immigration reform, and in late May, Trump threatened to impose tariffs on Mexico if it did not prevent migrants from passing through the country to the United States.

Since then, the number of people encountered at the southwest border, which includes asylum-seekers, has dropped to less than half the May rate.

McAleenan credited himself in a recent interview for this progress, saying it was the result of years of talks with Central American partners. U.S. officials have documented four such immigration surges over the past five years.