says Prof. Rick Hasen (Election Law Blog). [Note important update below.] The question, of course, is what will happen if he is reelected, but then resigns or is expelled. Rick's answer:
There's a bit of a dispute over which rules apply. The old rules (see here) provided for the governor to fill a vacancy and then to call a special election afterwards, if the term would expire in more than 30 months. A controversy over the last Alaskan governor appointing his daughter to a vacant Senate seat led Alaska voters to pass an initiative changing the law. Under the new law, the governor still may appoint a temporary person to the seat, who sits only until a special election is called in 60-90 days after the vacancy occurs. Because Senator Stevens' term would expire in more than 30 months, there's not much difference between these old and new laws, except as to the timing of the special election.
There's a constitutional question under the 17th Amendment whether [a change by voter initiative] to the means for filling Senate vacancies are constitutional. Vik Amar thinks it is. I'm not so sure (I address a similar, but not identical, issue in this paper).
So, either way, the governor will have the power to fill a vacancy at least for the short time (meaning this [Wall Street Journal] Washington Wire post is incorrect at the end).
Go to Rick's post for more, and for the links to the various other items he refers to.
UPDATE: Rick has a follow-up post:
More on Alaska Replacement Law, and Why the WSJ Washington Wire Was Right
Following up on this post, an alert reader points me to an Alaska Supreme Court case, State of Alaska v. Trust the People, 113 P.2d 613 (2005). The case involved a pre-election challenge to the initiative that changed the Alaska rules for replacing Senate candidates. In the case, the proponents of the initiative challenged a decision of the state's lieutenant governor to keep the measure off the ballot on grounds it was substantially the same as a law recently passed by the Alaska Legislature. The Alaska Supreme Court held that the lt. governor erred because the initiative and the measure were not substantially the same, because the initiative, unlike the new legislatively-enacted statute, did not provide for any temporary Senate replacement pending a special election. That is, under the initiative the Senate seat remains vacant until the special election is called, and the governor has no power to give the benefit of incumbency to a temporary appointee.
None of this was clear to me by looking at the Alaska Code, because the provision on vacancies remains part of the Code. (The initiative apparently was drafted before the code provision added by the state legislative statute, so the initiative did not call for its repeal.) So in the event Senator Stevens must be replaced, this conflict will have to be resolved, and the courts will have to confront a 17th Amendment argument, at least as to temporary replacements.