Wash. Rev. Code § 29A.60.150
The members of the county canvassing board may not include individuals who are candidates for an office to be voted upon at the primary or election. If no individual is available to serve on the canvassing board who is not a candidate at the primary or election the individual who is a candidate must not make decisions regarding the determination of a voter's intent with respect to a vote cast for that specific office; the decision must be made by the other two members of the board. If the two disagree, the vote must not be counted unless the number of those votes could affect the result of the primary or election, in which case the secretary of state or a designee shall make the decision on those votes. This section does not restrict participation in decisions as to the acceptance or rejection of entire ballots, unless the office in question is the only one for which the voter cast a vote.
RCW 29A.60.150