2018 US Senate Election cycle could be like the 2002 US Senate Election cycle.
In 2002- Bush's first midterm, Republicans picked up GA (Chambliss-R unseated Cleland-D),MN (Coleman-R replaced Wellstone-D),and MO special (Talent-R unseated Carnahan-D). Democrats picked up AR (Pryor unseated Tim Hutchinson). +2R.
In 2018-Trump's first midterm, I am predicting that Democrats will pick up AZ (Sinema-D unseats Flake-R) and NV (Titus-D unseats Heller-R). +2D
Republicans could pick up IN,MO,MT,and ND. Democrats hold onto FL,MI,MN,NM,OH,PA,VA,WV,and WI.
2020 US Senate Election cycle will be more Democratic friendly than the 2018 US Senate Election cycle.
The number of purple/red state Democratic US Senators up for re-election in 2020 4
1)MI-Peters-D
2)MN-Franken-D
3)NH-Shaheen-D
4)VA-Warner-D
I expect all of these Democratic incumbents to win re-election or if it were an open seat, Democrats will hold onto all of these states.
Democrats could pick up CO,GA if Ossoff decides to run,ME-if Collins retires,MT-if Bullock-D run,NC,and TX-if Cornyn-R retires and Castro-D runs.