President Donald Trump has selected Markwayne Mullin, a first-term senator from Oklahoma, to replace Kristi Noem as the new Secretary of Homeland Security. The announcement comes as the agency faces increasing scrutiny and is a central pillar of Trump’s domestic policy agenda.

Immigration Hardliner and Policy Alignment

Mullin, an enrolled member of the Cherokee Nation, is the first tribal citizen to serve in the U.S. Senate in nearly two decades. He has been a vocal supporter of Trump’s hardline immigration policies, including the controversial executive order ending birthright citizenship.

Shortly after the announcement, Mullin stated that his focus would be on securing the homeland and ensuring the Department of Homeland Security (DHS) works for the American people. He emphasized the need to address immigration policies that he believes are being exploited by individuals seeking to gain citizenship through birthright.

During a recent interview with NBC’s Meet the Press, Mullin argued that children born to undocumented immigrants should also be expelled from the country, stating, ‘Why wouldn’t you send a child with their parents? I mean, why would you want to separate them?’ He criticized what he described as an industry that exploits immigration laws by bringing people to the U.S. in their final month of pregnancy.

Mullin also defended the fatal shootings of Alex Pretti and Renee Good by federal immigration officers earlier this year. He claimed the officers had no choice but to engage Good, who was driving a vehicle that should be considered a deadly weapon.

Pugilistic Senator and Capitol Hill Presence

Mullin’s background as a former mixed-martial artist has influenced his presence on Capitol Hill. He gained notoriety during his time in the House for conducting intense, MMA-style workouts and using them to run for other members of Congress.

Mullin was serving in the House during the January 6, 2021, attack on the U.S. Capitol and assisted officers in barricading the doors to the House floor. He later said he would have physically dealt with the rioters if they had broken through.

During a 2023 Senate hearing, Mullin challenged Teamsters boss Sean O’Brien to a fight, highlighting his combative style. He later told CNN that physical confrontation could help address what he described as ‘keyboard warriors’ who avoid the consequences of their words.

Confirming the Nomination and Legal Implications

Trump’s announcement of Mullin’s nomination was somewhat vague. Noem said her last day would be March 31, 2026, and the president said Mullin ‘will become’ DHS secretary that same day. However, the position requires Senate confirmation, which is not within Trump’s control.

According to Thomas Berry, director of the Cato Institute’s Robert A. Levy Center for Constitutional Studies, Mullin cannot become the acting secretary unless he resigns his Senate seat and secures a non-Senate-confirmed position in the administration. This move would be legally dubious, Berry added, citing previous litigation over similar maneuvers.

If Mullin is not confirmed by March 31, the law requires the deputy secretary of DHS to become the acting secretary. The White House is confident that Mullin will be confirmed before the deadline, though uncertainty remains.

Once Mullin resigns, Oklahoma law gives Gov. Kevin Stitt 30 days to appoint a replacement. Since Mullin is a Republican, his replacement would need to be a registered Republican for at least five years. The appointee would also be required to submit an oath that they will not run for the seat when it comes up for election.

Because Mullin is scheduled to be up for reelection in November, there won’t be a separate special election. Instead, the winner of November’s election will be eligible to take office once the results are finalized.

The appointment of Markwayne Mullin to the position of Homeland Security secretary highlights the ongoing political and policy challenges facing the agency, as well as the broader implications for immigration and law enforcement in the United States.