Haw. Rev. Stat. § 17-1

(a) Except as provided in subsection (b), when a vacancy occurs in the office of United States senator , the vacancy shall be filled for the unexpired term at the following state general election; provided that the vacancy occurs not later than 4:30 p.m. on the twenty-first day prior to the date specified in section 12-6 for the close of filing nomination papers for regularly scheduled elections; otherwise at the state general election next following. The chief election officer shall issue a proclamation designating the election for filling the vacancy. All candidates for the unexpired term shall file nomination papers not later than the date and time specified in section 12‑6 and shall be nominated and elected in accordance with this title. Pending the election, the governor shall make a temporary appointment to fill the vacancy by selecting a person from a list of three prospective appointees submitted by the same political party as the prior incumbent. The appointee shall serve until the election and qualification of the person duly elected to fill the vacancy and shall be, at the time of appointment, and shall have been, for at least six months immediately prior to the appointment, a member of the same political party as the prior incumbent. The appointee shall be a resident of the State. If the prior incumbent was not a member of any political party, the governor shall appoint a person who is not and has not been, for at least six months immediately prior to the appointment, a member of any political party.

(b) Subsection (a) notwithstanding, when:

(1) A candidate other than the incumbent is duly elected to the office of United States senator at a general election; and

(2) The incumbent vacates the office at any time following the general election but prior to the expiration of the incumbent's term of office;

the governor, no later than the business day following receipt of official notice of the vacancy, shall temporarily appoint the person duly elected to succeed the incumbent to immediately fill the vacancy for the unexpired term. [L 1970, c 26, pt of §2; am L 1973, c 217, §7(a); am L 2007, c 57, §2; am L 2015, c 179, §1; am L 2018, c 214, §2]