WASHINGTON (AP) — Homeland Security Secretary Kristi Noem was ousted Thursday following sharp criticism during a congressional hearing earlier this week, where lawmakers questioned her leadership and decisions at the Department of Homeland Security.

President Donald Trump announced he had removed Noem from the post and plans to nominate Oklahoma Republican Sen. Markwayne Mullin to replace her.

The move came two days after a tense hearing on Capitol Hill in which both Republicans and Democrats pressed Noem over the administration’s immigration crackdown, disaster response efforts and a $220 million advertising campaign urging migrants in the country illegally to leave voluntarily. Some lawmakers questioned the spending and asked whether Trump had approved the campaign.

Trump later said he had not signed off on the ads, contradicting Noem’s testimony that the president had been aware of the initiative in advance.

Noem, the former governor of South Dakota, also faced scrutiny over the department’s handling of immigration enforcement and its response to disasters managed through the Federal Emergency Management Agency.

Trump said he intends to appoint Noem as a special envoy for a new initiative called “The Shield of the Americas,” focused on security cooperation across the Western Hemisphere.

Mullin’s nomination would require confirmation by the U.S. Senate, though he could serve as acting secretary while the nomination is pending under federal vacancy rules. Speaking briefly to reporters after the announcement, Mullin said he had not yet discussed a timeline for the confirmation process but looked forward to working more closely with the White House.