Wash. Const. art. III, § 4

The returns of every election for the officers named in the first section of this article shall be sealed up and transmitted to the seat of government by the returning officers, directed to the secretary of state, who shall deliver the same to the speaker of the house of representatives at the first meeting of the house thereafter, who shall open, publish and declare the result thereof in the presence of a majority of the members of both houses. The person having the highest number of votes shall be declared duly elected, and a certificate thereof shall be given to such person, signed by the presiding officers of both houses; but if any two or more shall be highest and equal in votes for the same office, one of them shall be chosen by the joint vote of both houses. Contested elections for such officers shall be decided by the legislature in such manner as shall be determined by law. The terms of all officers named in section one of this article shall commence on the second Monday in January after their election until otherwise provided by law.