JUNEAU -- State Natural Resources Commissioner Dan Sullivan plans to resign amid speculation that he will run for an Alaska U.S. Senate seat next year.
The news came as another Republican, Lt. Gov. Mead Treadwell, officially launched his campaign for Senate on Thursday.
Sullivan plans to resign effective Sept. 24. In his resignation letter to Gov. Sean Parnell, Sullivan said he intends to seek ways to serve his fellow Alaskans as he explores "new opportunities and challenges" in the next phase of his life.
Sullivan was returning from a conference in Asia and was not immediately available for comment. A Parnell spokeswoman said Sullivan sent the governor the letter Wednesday night.
Speculation has swirled around whether Sullivan will enter what would be an increasingly crowded race for the GOP nomination for the U.S. Senate seat currently held by Democrat Mark Begich. In addition to Treadwell, the GOP field currently includes Joe Miller, a tea party favorite during his unsuccessful bid to unseat fellow Republican Lisa Murkowski in the 2010 U.S. Senate race, and at least two lesser-known candidates, John Jaramillo and Kathleen Tonn.
Begich is in the midst of his first term.
Sullivan was appointed DNR commissioner in 2010. Before that, he served as Alaska attorney general and in the administration of President George W. Bush, as U.S. Assistant Secretary of State for Economic, Energy, and Business Affairs, according to his bio.
He was recently deployed to Afghanistan after being recalled to active military duty. According to his bio, Sullivan holds the rank of lieutenant colonel and is the executive officer of the 4th Marine Division's Anti-Terrorism Battalion, which is billed as the largest battalion in the Marine Corps Reserves.
Parnell, in a statement, said Sullivan "has been an instrumental part of my administration and his leadership will be missed."