Number of cycles it will take Democrats to get 60 US Senate seats.

[L. Coyote]

6. Your point? There are 34 seats up in 2018, of which 25 are held by Democrats.

Dems need to gain 3 seats to take control of the Senate with current 52 Republicans and 48 Democrats (including two independents).

http://www.270towin.com/2018-senate-election/

Democrats' Path Back to Power: Running the Numbers, Part 3 (Senate 2020)

......... To have even a remote chance of winning a Senate majority in 2018, Democrats will need all their incumbents to get re-elected (including five in states that went for Trump by more than 15 points), pick up Nevada and Arizona, and then squeeze one more win out of the group of Mississippi, Nebraska, Tennessee, Texas, Utah, and Wyoming ..........

........ bottom line is this: Democrats have to win some light-red and even solid-red Senate seats if they want to be back in the majority in the Senate by 2020. ..........