Wash. Rev. Code § 29A.80.031
If a vacancy occurs in the office of precinct committee officer by reason of death, resignation, or disqualification of the incumbent, or because of failure to elect, the respective county chair of the county central committee shall fill the vacancy by appointment. However, in a legislative district having a majority of its precincts in a county with a population of one million or more, the appointment may be made only upon the recommendation of the legislative district chair. The person so appointed must have the same qualifications as candidates when filing for election to the office for that precinct. When a vacancy in the office of precinct committee officer exists because of failure to elect at a state primary, the vacancy may not be filled until after the organization meeting of the county central committee and the new county chair has been selected as provided by RCW 29A.80.030.
RCW 29A.80.031