All of them are pandering to Sanders now, but only Warren is arguably in the Sanders wing. Maybe Gillibrand due to her position on health care.
It depends on how you’re defining the divisions within the party. I’d say there are three main things that differentiated Sanders from Clinton:
1) Position on the ideological spectrum. Clinton and Sanders disagreed on a number of policy positions, which (at least on economics and foreign policy) largely put Sanders to the left of Clinton.
2) Issue emphasis. Sanders focused heavily on economic issues, whereas Clinton’s policy focus was more diffuse, with her spending more time (at least compared to Sanders) talking about social issues and foreign policy issues.
3) Establishment vs. anti-establishment (or partisanship vs. ideology). Clinton was more establishmentarian and more of a supporter of the Democratic Party as an institution. (I mean, Sanders even identifies as an Indy rather than a Dem.)
Not all of these three things necessarily have to go together. In 2020, we’ll presumably see many more permutations along these three axes. E.g., on domestic policy at least, Sanders and Warren agree on almost everything, and, at least recently, Gillibrand also agrees with them on almost everything. (She’s co-sponsoring practically every bill that Sanders has his name on.) If the three of them were to debate, what would they even disagree on?
So on the ideological axis, at least if you believe what they’re saying today, there’s very little difference. But Sanders and Warren put far more emphasis on economic issues, while Gillibrand is the uber-feminist SJW. (Though she has recently spent more time trying to tie this feminism into bread and butter economic issues.)
Gillibrand’s also a lot more “partisan” and “establishmentarian” than Sanders is, while Warren is perhaps somewhere in between.
