The body consists of 49 members, each representing a district with a population of nearly 160,000.

Terms are staggered so that half the Senate is up for reelection every two years.

The state constitution allows both houses to write their own rules of procedure (article II, section 9) and to elect their own officers (article II, section 10) with the proviso that the lieutenant governor may preside in each house and has a deciding vote in the Senate, but that the Senate may choose a "temporary president" in the absence of the lieutenant governor.

The prevailing two-party system has produced current senate rules to the effect that the president pro tempore is nominated by the majority party caucus and elected by the entire Senate.

Lieutenant Governor Denny Heck is constitutionally the president of the Senate.