As Hillary Clinton continues to lose more female voters to her 74-year-old curmudgeonly socialist opponent (with whom she's now in a dead heat nationally), her campaign has launched a calculated attack on his supposedly sexist supporters, warning that Bernie Sanders risks allowing "crude" and "vitriolic" rhetoric to "creep further into the campaign."

Thursday the Clinton campaign issued a warning to Sanders that he must be more proactive in curbing the "demeaning and insulting" language of some of his supporters online, particularly the group known as the "Bernie Bros." His followers' "crudeness," team Clinton warned, could end up steering the campaign in an ugly, sexist direction.

"When you look at what goes online in particular, some of his supporters engage in negative, hurtful, nasty attacks and I think it is incumbent on him to call that out," said Clinton campaign manager Robby Mook Thursday at a Bloomberg Politics breakfast. "He needs to make sure that doesn't creep further into the campaign."

"Anyone who engages in social media in support of Hillary Clinton has encountered this element," added Clinton's national press secretary Brian Fallon. "It can be nasty. It can be vitriolic. And I think that the Sanders campaign needs to beware the extent to which, in an effort to mobilize and galvanize their supporters, they start to let the mentality or the crudeness seep into their own words and criticisms that they hurl at Secretary Clinton."

Though Mook and Fallon insisted that they were not criticizing Sanders' campaign for being overtly sexist itself, they fear he is not doing enough to squelch the "demeaning and insulting language." They also warned the Vermont senator not to allow any campaign ads to have any potentially sexist undertones.

Bloomberg notes that while Sanders' camp declined to respond to their report, his rapid-response director urged followers on Twitter to "be respectful."

Clinton, meanwhile, appears to be playing the Gender Card more than ever as of late, recently using it as "proof" that she's not a true establishment candidate. She's also recently complained about how much more "venomous" social media is for women, suggesting that she is a candidate who is unequally targeted online.