State Lawmakers Planned For Senate Vacancy Five Years Prior To Trump Picking Markwayne Mullin

The large Republican majority in the Oklahoma Legislature passed legislation in 2021 that now takes effect following President Donald Trump’s nomination of Republican Sen. Markwayne Mullin to be secretary of the Department of Homeland Security (DHS).

Trump announced Thursday that he would remove DHS Secretary Kristi Noem from her post, effective March 31, and nominated Mullin to replace her, pending Senate confirmation. If Mullin is confirmed by his Upper House colleagues, he will vacate the Senate seat he has held since 2022, prompting Oklahoma’s Republican Gov. Kevin Stitt to appoint a temporary replacement who, under a five-year-old state law, is required to sign an unenforceable document pledging not to run again. (RELATED: ‘He’s Respected’: Democratic Senator Praises Trump’s Pick to Replace Kristi Noem at DHS)

The Oklahoma state legislature passed SB 959 in May 2021 – which became law that same month with Stitt’s approval. The act “changes the procedures relating to filling a vacancy in the United States Senate,” according to the text of the bill.

“The Governor is responsible for appointing an eligible person to fill such office who has been a registered voter of his predecessor’s party in Oklahoma for at least 5 years within 30 days of the vacancy occurring,” the legislation continues. “The appointee may not run for the vacant position in a special election or regular election. »

SB 959’s co-author, Republican Oklahoma state Sen. Lonnie Paxton, told Oklahoma-based NPR affiliate KOSU that a form that appointees must sign indicating they will not run for re-election is “really not enforceable from the standpoint of excluding someone from the ballot.”

Oklahoma Governor Kevin Stitt is interviewed by David Rubenstein alongside Maryland Governor Wes Moore at the Economic Club February 18, 2026 in Washington, DC. (Photo by Heather Diehl/Getty Images)

Paxton, now president pro tempore of the Oklahoma Senate, explained that while an appointed state senator is not legally barred from running for another term after signing the document, the pledge operates on the honor system.

“[W]When the time comes, if someone were to run and be challenged…their opponents can certainly hold their own [the document] “The first thing this person did was lie to everyone and say they wouldn’t run for this office,” the state lawmaker told KOSU.

Paxton and his co-author, Republican and current State House Speaker Kyle Hilbert, proposed SB 959 in part to avoid unnecessary special election chaos, KOSU reported.

Hilbert told Oklahoma City-based ABC affiliate KOCO that he co-wrote the law at a time when Oklahoma was “one of the few states” in the United States that did not allow its governor to appoint a replacement to fill a vacant Senate seat. Paxton added that it meant even more at the time, given that the U.S. Senate was then split 50-50 between the Republicans and the Democratic caucus.

“[S]”If we had a vacant seat in the United States Senate, we would have to go through a special election process, which would have taken us several months to get there, and that seat would be vacant the whole time, and that would have tipped the power of the United States Senate,” Paxton told KOCO.

However, some legal experts say SB 959’s requirement that appointed senators pledge not to run again may not be consistent with the U.S. Constitution.

“There may be some interaction between the federal Constitution and state law that needs to be studied,” election law attorney AJ Ferate told Oklahoma-based NonDoc in November 2024, as rumors swirled that Trump might nominate Mullin for Interior secretary.

“It’s certainly a law that I’ve been asked about several times over the last few weeks,” Ferate, who previously chaired the Oklahoma GOP, added at the time.

Assuming Mullin is confirmed by the Senate and then resigns, and Stitt names a successor, it would be the second time the seat has changed occupants in the current six-year term.

The last regular election for Oklahoma’s Class II Senate seat was held in November 2020 when incumbent Republican Senator Jim Inhofe was re-elected to his fifth full term at the age of 85. Inhofe retired from the Senate at the end of the 117th Congress, triggering a November 2022 special election in which Mullin won. The longtime incumbent remained in the Senate until Mullin was sworn in in January 2023 and Stitt did not need to appoint an interim replacement during that time.

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