Republican held US Senate seats Democrats need to target in order to regain control of the

US Senate in 2018 and 2020.
2018-Democrats have to protect all of their vulnerable incumbents-Nelson-FL-if Scott-R runs,Donnelly-IN,McCaskill-MO,Tester-MT,Heitkamp-ND-if Cramer-R runs,Brown-OH,and Manchin-WV and pick up
NV(Heller-R) Rosen-D
AZ (Flake-R) Sinema-D or Stanton-D
TX (Cruz-R) O'Rourke-D is a long shot.
The maximum number of seats Democrats will have in the US Senate after the 2018 election is 50.
2020-All of the Democratic held US Senate seats up for grabs in 2020 are in states Democrats are likely to win at the Presidential
level-Peters-MI,Franken-MN,Shaheen-NH,and Warner-VA are going to win.
Democrats will need to target from highest priority to lowest priority is
1)CO (Gardner-R) Udall rematch, Hickenlooper, Perlmutter,Markey or Hancock are the likely Democratic nominee.
2)NC (Tillis-R) Hagan rematch, Kissell,McIntyre,Miller, or Foxx are the likely Democratic nominee.
3)AZ special (McCain-R succumbs from brain cancer-R) Sinema-D or Stanton-D are the likely Democratic nominee.
4)GA (Perdue-R) Nunn rematch, Carter, Barrow, or Reed are the likely Democratic nominee.
5)ME (Collins-R is vulnerable in the Republican primary) Pingree-D or Michaud-D are the likely Democratic nominee.
6)IA (Ernst-R) if and only if Vilsack-D runs.
7)MT (Daines-R) if and only if Bullock-D runs.
8)AK (Sullivan-R) if and only if Begich-D seeks a rematch
9)TX (if and only if Cornyn-R retires)one of the Castro twins is the likely Democratic nominee.