Oklahoma Gov. Kevin Stitt has appointed energy executive Alan Armstrong to replace outgoing Sen. Markwayne Mullin, who was confirmed to lead the Department of Homeland Security (DHS). Stitt praised Armstrong as a strong business leader who understands the power of free markets and limited government. He also aligned with President Trump on energy policy. Under state law, Stitt had 30 days to appoint someone from Mullin's party to temporarily fill the seat after the senator left his post.