Gov. Stitt to Pick Temporary Replacement After Trump Taps Sen. Markwayne Mullin to Lead DHS — Here Are the Reported Contenders for Oklahoma’s Senate Seat

Markwayne Mullin, the U.S. Senator from Oklahoma, was recently tapped by President Donald Trump to serve as Secretary of the United States Department of Homeland Security, replacing Kristi Noem following a shake-up in the administration.
President Donald Trump announced that Oklahoma Senator and undefeated MMA fighter Markwayne Mullin will lead the Department of Homeland Security (DHS) effective March 31.
The move, announced via Truth Social, signals a massive escalation in Trump’s war against the open-border radicals and “deep state” bureaucrats who have tried to sabotage the America First agenda.
“I am pleased to announce that the Highly Respected United States Senator from the Great State of Oklahoma, Markwayne Mullin, will become the United States Secretary of Homeland Security (DHS), effective March 31, 2026. The current Secretary, Kristi Noem, who has served us well, and has had numerous and spectacular results (especially on the Border!), will be moving to be Special Envoy for The Shield of the Americas, our new Security Initiative in the Western Hemisphere we are announcing on Saturday in Doral, Florida,” Trump said.
If Mullin is confirmed and leaves the Senate, Kevin Stitt, the Republican governor of Oklahoma, will be required to appoint a temporary replacement to serve until voters choose a senator in the next election.
Under Oklahoma law, Governor Kevin Stitt will have 30 days to appoint a temporary U.S. senator to fill the vacancy until voters decide the seat in the next election.
The appointee will serve only briefly and is expected to sign an oath promising not to run for the seat in the upcoming election, a measure designed to prevent the advantages of incumbency in the race.
Speculation is rampant about who Stitt might choose. Here’s a breakdown of the potential candidates, according to multiple outlets:
U.S. Rep. Kevin Hern: Hern who represents Oklahoma’s 1st Congressional District and chairs the Republican Study Committee.
Dustin Hilliary: A senior advisor to Governor Stitt, communications executive, and CEO of a telecommunications company.
Donelle Harder: Governor Stitt’s current chief of staff and long-time campaign consultant.
Harold Hamm: Founder of Continental Resources and a prominent oil executive. Hamm reportedly contacted Governor Stitt to express interest in the appointment.
John O’Connor: Former Oklahoma Attorney General, previously appointed by Stitt in 2021 to fill an unexpired term.
Nathan Dahm: Former chair of the Oklahoma Republican Party and current State Senator.
David Ostrowe: Chief Operating Officer in the Governor’s office.
Alex Gray: A former National Security Council official who ran for the Senate in 2022.
Bond Payne: Governor Stitt’s former chief of staff.
Matt Pinnell: The current Lieutenant Governor of Oklahoma, though his office has stated he is evaluating all options for his future service.
T.W. Shannon: Former Oklahoma House Speaker T.W. Shannon, a prominent conservative figure and member of the Chickasaw Nation, is also frequently mentioned. Shannon previously ran for the Senate.
Lt. Gov. Matt Pinnell: Some insiders have speculated that Lt. Gov. Matt Pinnell—a longtime Republican strategist and ally of Gov. Stitt—could be considered for the role.
Rep. Stephanie Bice: Another possible contender is U.S. Rep. Stephanie Bice, a Republican from Oklahoma City. Bice flipped her congressional district in 2020 and has built a reputation as a reliable conservative voice in Washington.
While the appointment is for a temporary placeholder, several prominent Oklahoma Republicans have already signaled interest in running for the seat permanently in the November 2026 general election, including U.S. Representatives Kevin Hern and Stephanie Bice. However, the temporary appointee cannot run in the election.
According to The Oklahoman, other Republicans who have filed paperwork to run for Oklahoma’s open U.S. Senate seat are:
- Nick Hankins
- Ron Meinhardt
- Tammy Swearengin
- Wayne Washington
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