After weeks of fundraising, Sen. Angus King formally announced his intention to seek a third term as U.S. senator.

King’s campaign announced Wednesday that the two-term senator submitted more than 5,000 signatures and qualified for the fall elections.

Sen. Angus King, I-Maine. Amanda Andrade-Rhoades/Associated Press, file

“It is the honor of my life to be hired by Maine people to work for them in Washington and back home in Maine to deliver a stronger future for the state we love,” King said in a written statement.

“I’m thrilled to have been a part of the significant bipartisan accomplishments in recent years that have created jobs, improved quality of life, protected our nation and those who step up to serve, and deliver a better tomorrow for our kids and grandkids – though there’s a lot left to do. I look forward to working with my colleagues on both sides of the aisle to build on this momentum.”

The announcement doesn’t come as a surprise, since King’s campaign website has been active and he has been actively raising money for months. Through the end of March, his campaign had raised $3.8 million with $2.5 million on hand.

The former two-term, Independent governor is facing three challengers in a race that will be decided by ranked-choice voting. His opponents have raised less than $200,000 combined.

Demi Kouzounas, of Saco, is running unopposed for the Republican nomination. The 68-year-old veteran, dentist and former chair of the Maine Republican Party has raised just under $174,000.

David Costello, of Brunswick, is running unopposed for the Democratic nomination and has raised about $72,000. The 63-year-old has held a variety of government and policy jobs over the years, including a stint as deputy secretary of Maryland’s Department of the Environment, and as interim Climate and Clean Energy Program director for the Natural Resources Council of Maine.

Last week, political newcomer Jason Cherry of Unity qualified as an Independent candidate for U.S. Senate. The former FBI agent who now works as a cybersecurity attorney said he’s running in support of age and term limits for congressmen.

Age has become an issue in both the presidential and Senate races this year.

King is one of two 80-year-olds, along with Bernie Sanders, 82, of Vermont, seeking reelection for another six-year term in the Senate.

In addition to the 54-year-old Cherry, the Maine Republican Party has been highlighting King’s age, calling on Republicans to send King a birthday card on his 80th birthday, and amplified national reporting on the number of senators serving into their 80s.

Efforts to make age an issue with King could be difficult in Maine, which is one of the oldest states in the nation. King remains one of the most popular senators in Maine and voters have expressed confidence in his ability to serve again if reelected, according to polling.

A recent poll by the University of New Hampshire’s Survey Center this spring found 65% of Maine voters expressed confidence that the 80-year-old incumbent is mentally and physically capable of serving another six-year term.

King currently serves on four committees, including those dealing with military, veterans and national security issues.

As a member of the U.S. Senate Committee on Armed Services, King currently leads the Subcommittee on Strategic Forces, which oversees the budgets for nuclear and strategic forces, as well as intelligence, space, cyberspace and ballistic missile defense programs, among others.

In addition to serving on the intelligence and veterans affairs committees, he also serves on the U.S. Senate Energy and Natural Resources Committee, where he leads the Subcommittee on National Parks.