Energy executive Alan Armstrong has been selected to fill Mullen’s Senate seat until the end of the year

OKLAHOMA CITY (AP) — Oklahoma’s governor on Tuesday appointed energy executive Alan Armstrong to serve in the U.S. Senate through the end of the year and ends the term of Republican Markwayne Mullen, the new Homeland Security secretary.

The selection of Republican Gov. Kevin Stitt, who has pledged to select a “conservative voice” to fill Mullen’s seat, elevated the former chairman and CEO of Williams, a major pipeline operator based in Tulsa, to the Senate.

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“He is a strong businessman who understands the power of free markets and limited government,” Stitt said.

Mullen, who was confirmed Monday to take over the Department of Homeland Security, was scheduled to run for re-election in November.

The final nine months of his term will now be served by Armstrong, who under Oklahoma law must agree not to run for a full term this fall. Republican US Representative Kevin Hearn quickly announced his candidacy for the Senate seat, and President Donald Trump has already endorsed him.

Armstrong, who has never served in elected office, has spent his career with Williams Companies, which employs about 5,800 people and specializes in gathering, storing and transporting natural gas. He became president and CEO in 2011 and moved to executive chairman last year.

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He is a longtime supporter of Stitt, giving him $8,500 in total campaign contributions since 2018, the maximum amount allowed under Oklahoma law.

Stitt, who will leave office in January and head the National Governors Association, was selected weeks after Trump criticized him following a dispute over who is allowed to attend the group’s annual meeting.

Former Tulsa Mayor Dewey Bartlett Jr. described Armstrong as a “moderate individual” who was more likely to build consensus around a decision rather than be driven by political ideology.

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Bartlett, whose father served in the U.S. Senate in the 1970s, said Armstrong’s knowledge of the energy industry and market factors also make him an ideal choice, especially as the Iran war shakes up the global flow of oil.

“I think that’s certainly a great approach, getting consensus on decision making,” said Bartlett, the head of an oil and gas company.

At hearings last week, Mullen tried to present himself as a steady hand for the lead agency following the firing of Kristi Noem, who has faced intense backlash over immigration enforcement and mass deportations carried out under her watch.