Alan Armstrong

Alan Stuart Armstrong (born July 11, 1962) is an American businessman and politician serving since 2026 as the junior United States senator from Oklahoma. A member of the Republican Party, he was the CEO of the oil and gas company Williams from 2011 to 2025.

Governor Kevin Stitt appointed Armstrong to the Senate after Markwayne Mullin resigned to become secretary of homeland security. Armstrong had never held office before his appointment. Under Oklahoma law, he is ineligible to run for reelection in 2026.

Alan Stuart Armstrong was born on July 11, 1962, in McLennan County, Texas. He was raised in Bartlesville, Oklahoma, where he graduated from Sooner High School. Both of his grandfathers, one grandmother, an uncle, and his parents worked for Phillips Petroleum.

Armstrong graduated from the University of Oklahoma with a bachelor's degree in civil engineering in 1985 and in 1986 started working as an engineer for the Williams Companies, an oil and gas company. He served as CEO and executive board chairman of Williams from 2011 to 2025. Armstrong also served as vice president of gathering and processing from 1999 to 2002; vice president of commercial development from 1998 to 1999; vice president of retail energy services from 1997 to 1998; and director of commercial operations for the company's Gulf Coast midstream operations from 1995 to 1997. Since January 2026, he has served as a director of Constellation Energy.

After the January 6 United States Capitol attack, Armstrong donated $5,800 to U.S. Representative Adam Kinzinger, a Republican who voted to impeach President Donald Trump in the attack's aftermath. Armstrong has also donated to the campaigns of senators John Barrasso, Tim Sheehy, Shelley Moore Capito, Mike Crapo, Josh Hawley, James Lankford, Joe Manchin, and Heidi Heitkamp.

In August 2022, President Joe Biden appointed Armstrong to the National Infrastructure Advisory Council.

On March 21, 2026, NOTUS reported that Governor Kevin Stitt would appoint Armstrong to the U.S. Senate after President Trump nominated incumbent senator Markwayne Mullin for secretary of homeland security. On March 24, Armstrong was formally announced as Stitt's choice for the appointment.

Armstrong was sworn in on March 24, 2026, by Senate president pro tempore Chuck Grassley. Per Oklahoma law, Armstrong is ineligible to run for reelection.

Armstrong has leaned on his background as an energy executive to draw attention to federal permitting reform. In June 2026, he joined a bipartisan Senate delegation to Ukraine.

On June 24, 2026, Armstrong introduced energy project permitting reform aimed to make it faster and easier to approve energy, pipeline, and mining projects by streamlining federal permitting and environmental reviews.

Armstrong lives in Tulsa with his wife, Shelly, and their four children.