The 31st Senate District falls entirely within the boundaries of Riverside County. Richard Roth (D) has been the incumbent since 2012 when he beat Republican Jeff Miller.
This district shows the following party registration for the three largest political groups (the source is http://www.l2political.com):
This seat has become less competitive over the years. Here are the 2016 primary results:
Richard Roth (D)- 61.2%
Richard Reed (R)- 38.8%
133,259 ballots were cast in this race. They had a re-match in November where Roth won by a similar margin.
In 2020, Roth much like Anthony Portantino in SD 25 ended up with no opponent.
This is another race that would have been tough for Republicans but would have benefited from having a challenger. Richard Roth is set for another four years.