Both sides, in good faith

The strongest fair case each way — we don't pick a winner.

The case for

Supporters of Sanders’ approach can argue that a national senator with limited staff, time and political capital must prioritise races where his involvement is most likely to be decisive or where candidates have sought and can use his support effectively. Selectivity can also protect the credibility of an endorsement, while allowing him to focus on legislative work and broader campaigns affecting many voters. The underlying value is responsible stewardship of finite political resources rather than an assumption that every progressive candidacy can be supported equally.

The case against

Critics can reasonably argue that Sanders has built a national movement around expanding progressive representation, so allies may fairly expect him to use his unusual reach to help credible candidates such as Francesca Hong, particularly in competitive state-level races. An endorsement can bring volunteers, donations and attention that candidates without comparable national profiles struggle to obtain, and choosing not to intervene may weaken the wider network that has supported Sanders’ own agenda. The underlying value is solidarity: prominent movement leaders should show up for allies when their support could materially strengthen the cause.