Tulsa energy exec Alan Armstrong sworn in to replace Sen. Mullin
Oklahoma Governor Kevin Stitt appointed Tulsa energy executive Alan Armstrong to fill the Senate vacancy left by Markwayne Mullin’s confirmation as Homeland Security Secretary, making Armstrong an interim senator focused on accelerating infrastructure and permitting reform. Armstrong, a long-time Williams Companies leader, inherits a pivotal energy-policy moment and aims to break federal approvals deadlocks to bolster U.S. competitiveness, while maintaining the current Republican Senate balance. His interim tenure extends to the 2026 election outcome and certification, with a sworn pledge not to run for the seat. In parallel, Republican Rep. Kevin Hern emerges as the leading candidate for the permanent seat, buoyed by a Trump endorsement, as the party prepares for a June primary. The move signals a technical pivot toward energy-focused policy without altering party control in the chamber, setting up the next phase of debates on the America First energy agenda.
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Armstrong was sworn in as an interim U.S. senator and will serve until the November 3, 2026 general election results are certified, with the term concluding in early 2027. He pledged not to seek election to the seat in that cycle, per Oklahoma law accompanying interim appointments.
Armstrong’s four-decade tenure at Williams Companies, including 14 years as CEO, is expected to shape his focus on permitting reform and streamlining regulatory processes for large-scale energy projects.
The appointment comes after Mullin’s 54-45 confirmation to lead the Department of Homeland Security, a move that leaves the Senate’s 53–47 Republican majority unchanged but elevates energy policy as a central area of debate.
Oklahoma’s vacancy rules require the interim appointee to be from the same party as the departing senator for at least five years and to sign an oath not to pursue the seat, ensuring no incumbency advantage.
Republican Rep. Kevin Hern of Oklahoma’s 1st District is positioned as the leading candidate for the permanent seat, aided by an early endorsement from President Trump and minimal challenge from Stephanie Bice for the party’s June primary.
Stitt and Armstrong indicated consultations with Trump and Senate Majority Leader Thune, framing Armstrong as a technically adept, business-minded leader who can advance permitting reform and infrastructure goals in Congress.