Yes, Democrats do have a legitimate path to win back the Senate
https://www.nbcnews.com/politics/first-read/yes-democrats-do-have-legitimate-path-win-back-senate-n907446
WASHINGTON The takeaway from the trio of NBC/Marist polls we released this week is that, yes, Democrats do have a legitimate path to retaking the Senate in November. Given the Senate map, its probably not the most likely outcome. But its a real possibility more than most people might think.
With the GOP controlling the Senate by a slim 51-to-49 margin after the Dems surprising win in Alabama late last year Democrats must gain a net of two Senate seats to take back the chamber (since Vice President Mike Pence can break a 50-50 tie). And their path to gaining those two Senate seats is: 1) by winning the GOP-held seats of Arizona and Nevada and holding on to ALL of their vulnerable seats in Florida, Indiana, Missouri, North Dakota and West Virginia, or 2) by winning Arizona, Nevada AND Tennessee, and losing just one of their vulnerable states. (FYI: If Democrats somehow win Texas, theyre definitely winning the Senate.)
So what do our NBC/Marist polls show? Well, Democrats lead in Indiana and Tennessee (although within the margin of error), while its tied in Missouri.
Heres another way to look at the battle for Senate control: The Cook Political Report identifies eight total toss-up races five held by Democrats (Florida, Indiana, Missouri, North Dakota and West Virginia) and three held by Republicans (Arizona, Nevada and Tennessee). To win control, Democrats will need to win seven of these eight toss-up races.