President Trump fired DHS Secretary Kristi Noem on March 5, 2026, making her the first Cabinet secretary to depart his second term, and announced Oklahoma Senator Markwayne Mullin as her replacement effective March 31. The firing came one day after two consecutive days of combative congressional hearings in which Noem faced intense scrutiny over DHS tactics in Minnesota, the $220 million taxpayer-funded ad campaign, and her relationship with special government employee Corey Lewandowski.
The immediate trigger was the ad campaign controversy. During Senate testimony on Tuesday, Noem claimed Trump had personally approved the $220 million "Stronger Border, Stronger America" ad blitz in which she featured prominently. Trump told Reuters he had not signed off on the campaign. Senator John Kennedy (R-LA), who had grilled Noem about the ads, told reporters Trump was "mad as a murder hornet" after their conversation following the hearing.
An administration official told NBC News the firing was due to "a culmination of her many unfortunate leadership failures including the fallout in Minnesota, the ad campaign, the allegations of infidelity, the mismanagement of her staff, and her constant feuding with the heads of other agencies, including CBP and ICE." The Minnesota fallout referred to aggressive DHS/ICE enforcement operations that had drawn sustained public backlash and legal challenges. The infidelity allegations involved Noem's relationship with Corey Lewandowski, the political operative who had operated as de facto DHS chief of staff without formal title, security clearance, or Senate confirmation.
Trump announced Noem would be reassigned as Special Envoy for the "Shield of the Americas," a Western Hemisphere security initiative to be announced Saturday. The move appeared designed to soften the firing by providing a face-saving title, though the position carries no statutory authority or confirmed portfolio.
Mullin, a Republican senator since 2023 who previously served 10 years in the House representing Oklahoma's 2nd congressional district, is a Cherokee Nation citizen, former MMA fighter, and hardline immigration hawk aligned with Trump's border enforcement agenda. He serves on the Senate Armed Services and Appropriations committees. Under federal law, Mullin can serve as acting DHS Secretary while his nomination is formally pending before the Senate. Senator John Fetterman (D-PA) announced he would vote to confirm; Senate Minority Leader Chuck Schumer declared himself "a resounding NO."
The transition raises several significant questions for the institutional capture narrative. Noem's tenure was defined by the implementation of Stephen Miller's mass deportation agenda, the $220M ad campaign corruption exposed by ProPublica, the weaponization of ICE in sanctuary cities, and the Minneapolis shooting of U.S. citizen Renee Nicole Good. Whether Mullin will continue these policies or chart a different course at DHS — and whether the shadow governance structure built by Lewandowski will survive the leadership change — remain open questions. Mullin's nomination also creates a Senate vacancy in Oklahoma that Governor Kevin Stitt will fill by appointment.