So why is the map so limited? The vague notion that 2020 should present so many more pickup opportunities for Democrats stems from the seesaw feeling we’ve become inured to over the last few Senate cycles. What this misses, and what should be so frightening for Democrats looking at their Senate prospects down the road, is how many of those 2014 Republican pickups Democrats have no chance of taking back.

Republicans picked up four seats in 2014 from retiring Democrats: South Dakota Sen. Mike Rounds won Sen. Tim Johnson’s seat, West Virginia Sen. Shelley Moore Capito won Sen. Jay Rockefeller’s seat, Iowa Sen. Joni Ernst won Sen. Tom Harkin’s seat, and Montana Sen. Steve Daines won Sen. Max Baucus’ seat. (Baucus had given up his seat to serve in the Obama administration; his appointed replacement, John Walsh, dropped out of the race over a plagiarism scandal.) These Republicans aren’t going anywhere. Once the senior Democrats that had held those seats for decades retired, they were Republicans’ for the taking—and the keeping.

Incumbent Democrats were also defeated in 2014 in Arkansas, Louisiana, and Alaska by Republicans who will not lose those seats in 2020.

Rather than a pendulum shift in Democrats’ favor, the 2020 Senate election is shaping up to be the moment when the organic Republican majority within the Senate falls into place.