March 24 (Reuters) - Oklahoma's governor said on Tuesday

he was appointing energy executive Alan Armstrong to represent

the state in the U.S. Senate, filling a vacancy created after

Markwayne Mullin was confirmed as U.S. Homeland Security

Secretary.

* Governor Kevin Stitt announced Armstrong's appointment in

a post on X, calling him a "staunch conservative" who will help

advance energy reform efforts.

* Armstrong is the executive chairman and former CEO of

Williams Companies ( WMB ), an energy infrastructure company

based in Tulsa, Oklahoma.

* "I have no doubt that his perspective will be influential

in moving the needle on permitting reform to unlock American

competitiveness and energy affordability for generations to

come," Stitt said of Armstrong.

* Armstrong will replace Mullin until a new senator is

elected to fill the seat in November's midterm elections.

Armstrong is barred under Oklahoma law from running as a

candidate in that election.

* The Senate voted 54-45 on Monday to confirm Mullin as

Homeland Security Secretary, replacing Kristi Noem. Mullin was

scheduled to be sworn in on Tuesday at a ceremony at the White

House.