Kristi Noem is on her way out at the Department of Homeland Security after a tenure marred by personal controversies and an unpopular immigration crackdown. The big picture: Noem has long been a target for Democrats, but her leadership also angered some congressional Republicans . She becomes the first Cabinet secretary to be removed from their post in President Trump 's second term. Driving the news: Trump announced Thursday that he plans to tap Sen. Markwayne Mullin (R-Okla.) to replace Noem. Noem will move to a position as special envoy for the Shield of the Americas, a "new Security Initiative in the Western Hemisphere" that Trump said will be announced Saturday. Here are the controversies that led up to Noem's departure: 1. Alex Pretti comments Noem came under fire for claiming that Alex Pretti, a protester who federal immigration agents shot and killed in Minnesota, wanted to "kill" agents and "committed an act of domestic terrorism." The incendiary and misleading rhetoric set off a blame game within the administration. Catch up quick: The DHS statement shared to X soon after Pretti was killed said an agent "[f]earing for his life" fired "defensive shots" after attempting to "disarm" Pretti, saying it "looks like a situation where an individual wanted to do maximum damage and massacre law enforcement." Noem also inaccurately said Pretti was "brandishing" his weapon. Bystander videos showed Pretti never reached for his gun and had been disarmed before he was shot. 2. Ad blitz DHS spent millions on ads promoting Trump's mass deportation agenda through videos starring Noem. Sen. John Kennedy (R-La.) questioned Noem in early March during a congressional hearing about how the ads square with her "concern for [government] waste." Noem responded that Trump "tasked me with getting the message out to the country" and beyond. The intrigue: Noem was also pressed on whether Trump asked her to run the advertisements. She said that they "had that conversation, yes, before I was put in this position ... and since then as well." Multiple outlets reported that Noem's contention that Trump approved the ad blitz enraged the president. A ProPublica investigation uncovered ties to a company run by Noem's former chief spokesperson's husband. Noem said she had nothing to do with picking the contractors for the ads. 3. Luxury jets Noem's plan to use border funds for a multi-million-dollar jet fleet horrified top officials . Noem purchased two Gulfstream G700 luxury jets. A third plane, a Boeing 737, was being leased with plans to buy it for about $70 million. The funding comes from the One Big Beautiful Bill's DHS infusion. Pressed about the jets in her recent Senate hearing, Noem said they were used for "long-range command and control aircraft" and said purchasing the aircraft will "save the taxpayers hundreds of millions of dollars." A DHS spokesperson told Axios in a statement late last month, "Anyone who runs a business in the real world will tell you that owning a work vehicle is less expensive than dealing with long-term rental costs." 4. Lewandowski's role Corey Lewandowski, a top aide acting as Noem's de-facto chief-of-staff, has been a source of controversy himself. A Wall Street Journal report about Lewandowski firing a pilot over Noem's misplaced blanket became new fodder for her critics. Once Noem's political adviser, his outsized influence at DHS as a "special government employee" has raised eyebrows . 5. A Capitol Hill castigation Noem's final appearance on the Hill as a Cabinet secretary drew a number of fiery rebukes from both sides of the aisle. Sen. Thom Tillis (R-N.C.) called her a "disappointment" and said that "what we've seen is a disaster under your leadership." He had previously called for her to resign. He also cited a letter from DHS's Office of the Inspector General as evidence of Noem's leadership missteps, saying the office has "10 different instances under Ms. Noem's leadership where they've been misled and not allowed to pursue investigations that they think are critically important." The bottom line: As Americans sour on Trump's immigration crackdown, there's no guarantee the DHS drama will end with Noem's departure. Go deeper: Scoop: 200 miles of Trump's border wall held up by Noem's DHS