Don Young plans to make it official on Wednesday.
Young's campaign says he will file for re-election at the Division of Elections office in Anchorage.
Young, a Republican, is seeking his 21st two-year term as Alaska's sole representative in the U.S. House.
At least four other candidates, who are little known, have already filed to run. They are Republican John Cox of Anchor Point, Libertarian Jim McDermott of Fairbanks and Democrats Doug Urquidi of Eagle River and Frank Vondersaar of Homer.