Hurtado won the open 12th District seat while Caballero defeated Republican Sen. Andy Vidak in the neighboring 14th District. Both are in the Fresno area. Vidak, of Hanford, has held the seat since a special election in 2013.
The victories give Democrats a two-thirds advantage in the 40-member Senate. The party also has that advantage in the 80-seat Assembly. The party also holds every statewide office, led by Gov.-elect Gavin Newsom.
Two-thirds majorities allow Democrats to raise taxes, suspend legislative rules and override vetoes without Republican votes.