This is such a great question. And to be clear- Ds should be able to win both of these states in 2020. But of the 2, its AZ and its not even close. A+ senate nominee in a state that flipped in '18 & AZ is actually a story of both turnout & persuasion bc Never Trump/McCain Rs.
A small, and mean small, group of whom appear to have strategically voted against McSally in the 2018 cycle bc both the CNN exits & other data I've looked at show that only 88% of Rs voted for the R senate candidate there. That is 2 pts higher than the normal break down & AZ was
the ONLY state we saw something like that happen in for Rs (I have an article I am working on for this) other than WVA, which is still a "historical Dem" realignment where a significant % of Rs are casting ballots for Manchin, but Manchin will likely be the last D they vote for
now that the other dude that was in this position, Jim Justice, changed his party reg to R. Anyway, back to AZ. If Ds drop AZ in 2020 it will only be via gross incompetence, which I assure you, they are perfectly capable of. But they SHOULD be able to win it. Their weak spot is
failing to invest in the proper resource allocation between the traditional "medium voter" GOTV targeting & Latino mobilization. However, they were inept at this in '18 & still had enough Trump bump (while failing to purposely exploit it at all) to cross the finish line so they
can actually still win there even with sub-par strategy, which is what my modeling assumes (always a safe assumption!) That said, I have seen evidence of significant Latino investment coming so.....
