For the fifth time in just under three years, the Trump administration finds itself looking for another Department of Homeland Security (DHS) secretary, after acting Secretary Kevin McAleenan said he would step down.

McAleenan, an Obama administration holdover who replaced the embattled former DHS Secretary Kristjen Nielsen, tendered his resignation just a few days after pro-immigrant protesters drowned out his speech at an event at the Georgetown University Law Center.

While McAleenan has been credited by the president and others for reducing crossings at the southern border and thanked Trump for his efforts to secure the border, he more recently expressed dismay over the politicization of DHS, saying in a Washington Post report that he didn’t have control over “the tone, the message, the public face and approach of the department in an increasingly polarized time.” 

His resignation comes after an ongoing purge at DHS. Trump said he would announce a replacement for McAleenan later in the week.

“DHS is a critical national security department charged with keeping the country safe, but under this administration, President Trump has forced the Department to stray from its core counterterrorism mission to be almost singularly focused on his xenophobic and cruel immigration agenda,” said Rep. Bennie Thompson, D-Miss., chairman of the House Homeland Security Committee, who dinged Trump for continuing to “decimate the leadership” of DHS.

Thompson called on the president to nominate a permanent secretary who could easily obtain Senate approval. “President Trump cannot continue to rely on instilling ‘acting’ – and potentially unlawful – figureheads for this critical position,” the lawmaker said. “The next Secretary must be able to convey to the American people that the federal government is focused on keeping the country safe from the top threats we face.” DHS is due before Thompson’s committee on Oct. 30 to testify “on threats to the homeland.”