So, what’s changed? I’d argue that Sanders was benefiting from not being in a competitive campaign. (Former Vice President Joe Biden, who has garnered the most support in general election polls among the Democrats, may be benefiting from a similar effect.) When you’re not being thought of a viable threat to win a party’s nomination, opponents tend to lay off. The last time Sanders was thought of as at least a minor threat to win the Democratic nomination was in March 2016. His net favorability rating back then among all voters was +3 points in a CNN poll.
The good news for Sanders is that his net favorability rating is at about the same level as the other people who have declared their candidacy for the Democratic nomination. Most of these other candidates, however, are relatively unknown. At least at this point, it’s not the case that Sanders is less electable than the average Democrat. It’s just that he cannot make the case that he is more electable based on national polling.
Sanders, though, may have to convince Democratic voters that he electable. In our poll, just 30% of Democratic voters believe the party has a better chance of winning the presidency with him than someone else as the nominee. The vast majority, 59%, think they have a better shot of winning with someone else.