President Trump announced Thursday his nomination of Senator Markwayne Mullin (R-Okla.) to serve as Secretary of the Department of Homeland Security, replacing Kristi Noem in the position.

The nomination creates a vacancy in the U.S. Senate that Oklahoma Governor Kevin Stitt will need to fill. Under state law, Stitt has 30 days to appoint a replacement from the same political party once Mullin officially leaves his Senate seat.

Mullin, who has served in the Senate since 2023, previously represented Oklahoma's 2nd Congressional District in the House of Representatives from 2013 to 2023. Before entering politics, he operated a plumbing business and competed as a mixed martial arts fighter.

The Department of Homeland Security oversees immigration enforcement, cybersecurity, disaster response, and transportation security among other critical functions. If confirmed by the Senate, Mullin would lead an agency with approximately 260,000 employees and an annual budget of over $60 billion.

The nomination comes as the incoming administration prepares to implement its immigration and border security priorities. Mullin's appointment would need Senate confirmation before he could officially assume the role.