2018 Iowa Senate election  The 2018 Iowa State Senate elections took place as part of the biennial 2018 United States elections. Iowa voters elected state senators in half of the state senate's districts--the 25 odd-numbered state senate districts. State senators serve four-year terms in the Iowa State Senate, with half of the seats up for election each cycle. The primary election on June 5, 2018 determined which candidates appeared on the November 6, 2018 general election ballot. Primary election results can be obtained here. Following the previous 2016 Iowa Senate election, Republicans flipped control of the Iowa state Senate, taking control away from the Democrats. To reclaim control of the chamber from Republicans, the Democrats needed to net 6 Senate seats. Republicans expanded their control of the Iowa State Senate following the 2018 general election, increasing their majority from 29 to 32 seats. Democrats saw their numbers dwindle from 20 to 18 seats. The lone Independent member of the IA state Senate was replaced by a Republican as well. Source:    Source: