Trump Fires Kristi Noem as DHS Secretary, Nominates Sen. Markwayne Mullin as Replacement

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 intended replacement. 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. Mullin was not sworn in until March 24, 2026, following Senate confirmation on March 23 (see 2026-03-24–mullin-sworn-in-as-dhs-secretary) — contemporaneous March 5 reporting characterized his takeover as “effective March 31,” but that date did not hold.

Immediate Cause

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, and separately told reporters “I didn’t know about it. I wasn’t thrilled with it.” 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. The public contradiction between Noem’s sworn testimony and the president’s disavowal created an irreconcilable credibility problem.

Broader Context

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 (Operation Metro Surge) that had drawn sustained public backlash, legal challenges, and the shooting deaths of two U.S. citizens by federal agents, including Alex Pretti (see 2026-01-24–alex-pretti-killed-by-cbp-minneapolis). 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.

Noem had also faced criticism for a $220 million no-bid advertising contract that bypassed competitive bidding requirements, and for her refusal to cooperate with a DHS Inspector General investigation. Republican Sen. Thom Tillis had called her leadership “a disaster” at the same March 3-4 hearing, threatening to block administration nominees unless she answered outstanding accountability questions. Trump also privately expressed frustration that Noem had become more prominent than the administration’s enforcement brand could absorb — her horseback advertisement at Mount Rushmore, produced with federal funds, had attracted bipartisan ridicule as self-promotion masquerading as government communications.

The Reassignment: Shield of the Americas

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, and its parameters were not publicly defined at the time of the announcement.

The Nomination: Markwayne Mullin

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. Trump’s selection of Mullin signaled the administration’s intent to install a loyalist with a pugilistic public profile rather than a managerial technocrat. Under federal law, Mullin was positioned to serve as acting DHS Secretary while his nomination was 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.” Mullin’s nomination also created a Senate vacancy in Oklahoma that Governor Kevin Stitt would fill by appointment.

Significance

Noem’s removal marked the first Cabinet casualty of Trump’s second term and signaled the administration’s willingness to discard figures who became politically inconvenient even when their enforcement records were largely aligned with the president’s agenda. The episode illustrated how the administration managed accountability: not through institutional reform of DHS conduct — the court contempt proceedings, the killed U.S. citizens, the inflated statistics — but through personnel replacement directed at restoring political optics. The appointment of Mullin over a managerial candidate suggested enforcement escalation rather than recalibration was the intended trajectory, though Mullin’s actual first-days record after confirmation (see 2026-03-24–mullin-sworn-in-as-dhs-secretary) diverged from that reading in several procurement and operational respects.

The transition raised 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 Alex Pretti. Whether Mullin would continue these policies or chart a different course at DHS — and whether the shadow governance structure built by Lewandowski would survive the leadership change — were the open questions this firing raised.

Related Timeline Entries

• 2026-03-06–noem-firing-aftermath-dhs-tenure-controversies — Five-controversy post-firing catalog
• 2026-03-07–shield-of-americas-summit-trump-doral-cartel-coalition — Noem’s formal debut as Shield of the Americas envoy
• 2026-03-24–mullin-sworn-in-as-dhs-secretary — Mullin’s actual Senate confirmation (March 23) and swearing-in (March 24); first-days policy record
• 2026-04-17–stateline-dhs-compromises-warehouse-detention-centers — Downstream warehouse-detention scale-backs under Mullin