Karen Keiser Democratic Karen Keiser Democratic The 2018 Washington State Senate elections took place as part of the biennial United States elections.

Each candidate is allowed to write in their party preference so that it appears as they desire on the ballot.

However, in 2017 Democrats regained control of the Washington State Senate after Democrat Manka Dhingra won a special election in Washington's 45th legislative district.

Democrats expanded their caucus's majority to 28–21 by further flipping the 26th, 30th, and 47th districts.

Tim Sheldon was reelected as a Democrat, but continued to caucus with the Republicans.