Washington • President Donald Trump fired his embattled homeland security secretary, Kristi Noem, on Thursday and announced plans to replace her with Sen. Markwayne Mullin of Oklahoma, after she was grilled by Republican lawmakers this week at congressional hearings on a variety of topics, including her knowledge of a lucrative advertising contract.

Trump announced the change on social media, along with a new, and previously nonexistent, role for Noem: special envoy for the Shield of the Americas, which he said would be a new security initiative for the Western Hemisphere.

Trump is close with Mullin, a Republican, and speaks with him regularly.

Noem — the first Cabinet member to be ousted in Trump’s second term — had been among the key figures in the administration fulfilling his mass deportation effort, which he campaigned on aggressively and which was heavily influenced by Stephen Miller, a top White House adviser.

But her tenure had been marked by a string of controversies, and her fate had been the focus of speculation among Trump’s allies for several weeks. On Thursday, the president contradicted remarks that Noem made under penalty of perjury in her hearing before a Senate panel on Wednesday: that Trump had signed off ​on a border security advertising campaign featuring Noem.

“I ​never knew anything about it,” ​Trump told Reuters. A White House spokesperson declined to comment, and referred a reporter to Trump’s comments to Reuters.

Noem has faced scrutiny ​from lawmakers about the campaign, on which the government spent $220 million. The firm handling it was connected to the husband of Noem’s former spokesperson.

The ads prominently featured Noem, including in a scene filmed on horseback at Mount Rushmore in ​the former ​South Dakota governor’s home state.

Pressed at a separate hearing Tuesday about the process for awarding the contracts behind the ad campaign, Noem said that it all went through “a competitive ​process,” and that no political appointees were involved. On Wednesday, she said the contract was “all ​done correctly, all done ​legally.”

Sen. John Kennedy, R-La., forcefully questioned Noem over ad contracts. Kennedy told reporters Thursday that he received a call from the president about her testimony. “Put it this way,” he said. “His recollection and her recollection are different.”

This article originally appeared in The New York Times.