> If Biden cared, he could shame these "Democrat" senators and prevent them from getting re-elected. If he uses his platform to inhibit their campaign fundraising, they will surely change positions out of fear of loosing their seat.

Manchin is more popular than Biden in WV, and his positions do more to support his fundraising than Biden’s opposition would do to hurt it. Biden can't meaningfully hurt Manchin.

Sinema presents the opposite problem: she's already completely alienated the Democratic primary electorate. She clearly isn't interested in being reelected (or, if she does care, its not as a Democrat), so there's no leverage there.