Trump selects Oklahoma Sen. Markwayne Mullin for Homeland Security secretary role as Kristi Noem exits

Announcement sets March 31 target date and triggers Senate confirmation process

President Donald Trump said Thursday that Oklahoma Sen. Markwayne Mullin will be his next secretary of the Department of Homeland Security, a Cabinet post that oversees immigration enforcement, border security, cybersecurity coordination and disaster response. The White House-designated change would take effect March 31, 2026, pending Senate confirmation.

The move follows Trump’s decision to remove Homeland Security Secretary Kristi Noem, who has led the department since the start of the administration’s second term. In the same announcement, Trump said Noem would shift into a new role tied to a Western Hemisphere security initiative described as “the Shield of the Americas.”

Why the DHS job change matters

DHS is among the largest federal departments, combining agencies with distinct missions and cultures, including Customs and Border Protection, Immigration and Customs Enforcement, the Transportation Security Administration, the Secret Service, the Cybersecurity and Infrastructure Security Agency, and the Federal Emergency Management Agency. A change at the top can affect priorities across enforcement operations, interagency coordination and budget requests.

Noem’s final days in the role came amid heightened congressional scrutiny of the department, including oversight hearings focused on DHS enforcement tactics and high-profile incidents involving federal immigration officers. Lawmakers have also been debating DHS funding, a recurring flashpoint as the administration pursues its immigration agenda.

Who is Markwayne Mullin

Mullin, a Republican, has served in the U.S. Senate since 2023 after multiple terms in the U.S. House representing eastern Oklahoma. A former mixed martial arts fighter and plumbing business owner, Mullin has been a prominent defender of the administration’s border and immigration policies and has remained active on federal funding and security-related issues affecting Oklahoma.

If confirmed, Mullin would move from the legislative branch to an executive role responsible for day-to-day management of sprawling operational agencies and a workforce numbering in the hundreds of thousands.

What happens next

The nomination is expected to proceed through Senate committee review and a full Senate vote. Until a new secretary is confirmed and sworn in, DHS leadership would typically rely on the department’s established succession and delegation structure to manage operations.

• Nomination: The president submits the nomination to the Senate.

• Hearings: A Senate committee conducts vetting and questioning.

• Vote: The full Senate votes on confirmation.

The administration has set March 31, 2026, as the intended effective date for the leadership change, contingent on Senate action.

For Oklahoma, the nomination elevates a sitting U.S. senator to a top national security post while raising the near-term question of how the state’s Senate delegation would change if Mullin is confirmed and resigns his seat.