Support for embattled Maine Senate candidate Graham Platner is cratering among Democrats, with one of his most prominent supporters calling on him to exit the race following a harrowing rape allegation.Rep. Ro Khanna, D‑Calif., rescinded his endorsement and called on Platner to suspend his campaign following a bombshell Politico report detailing a rape allegation by Maine resident Jenny Racicot, 41, who previously dated the scandal-plagued candidate.Platner immediately denied Racicot’s account — which alleges that he barged into her home in 2021 and forced her to have unprotected sex — but has said his campaign is determining its next steps.“I’ve been very clear that sexual assault or violence against women is a red line,” Khanna said in a post on social media Monday evening. “These all …