Vermont Sen. Bernie Sanders has always faced an uphill battle in is campaign to be the Democratic nominee in 2016. That he has managed to mount a competitive challenge to the frontrunner, Hillary Clinton, probably means something relating to his ability to inspire and mobilize certain groups of voters, or the inherent weakness of frontrunner and former Secretary of State Hillary Clinton, or both. But his chances of winning the nomination are grim at this point, according to Milo Beckman over at the numbers-crunching site FiveThirtyEight.com:
...[B]arring some catastrophic news event, Sanders will not win the Democratic nomination for president in 2016. In fact, most past candidates in Sanders’s position dropped out long before this point in the race, and those who stayed in made little pretense of winning. (The Sanders campaign, which announced Wednesday it was laying off a ton of staff, may be recognizing this.)
Historically speaking, Democratic primary races do not have many twists and turns. Rather, the eventual winner tends to take an early lead — on or before Super Tuesday — and stay there. Runner-ups can kick for a while, but they tend to concede the race by February or early March.
As it stands, Sanders is firmly in runner-up territory. He is losing 9 million to 12 million among those who have already voted, and polls show him lagging by an average of 8.8 percentage points in the states yet to vote1. Sanders has gained substantially in national polls but is still the less popular candidate (outside of the Bernietopia that is social media).
Beckman goes on to compare Sanders' performance and path forward to the 2008 nomination contest between Clinton and Obama, and provides a great deal of interesting analysis and insight that is worth the time to read in detail.