Wash. Rev. Code § 29A.56.360
In a year in which the president and vice president of the United States are to be elected, the secretary of state shall include in the certification prepared under RCW 29A.52.321 the names of all candidates for president and vice president who, no later than the third Tuesday of August, have certified a slate of electors to the secretary of state under RCW 29A.56.320 and have been nominated either (1) by a major political party, as certified by the appropriate authority under party rules, or (2) by a minor party or as independent candidates. Major or minor political parties or independent presidential candidates may substitute a different candidate for vice president for the one whose name appears on the party's certification or nominating petition at any time before seventy-five days before the general election, by certifying the change to the secretary of state. Substitutions must not be permitted to delay the printing of either ballots or a voters' pamphlet. Substitutions are valid only if submitted under oath and signed by the same individual who originally certified the nomination, or his or her documented successor, and only if the substitute candidate consents in writing.
RCW 29A.56.360