Senator Sanders' surprisingly popular campaign for the Democratic presidential nomination has often been described as one the populist phenomena of this moment in American history. For the most part, this is because of the anger Sanders and his supporters express towards Wall Street, as well as their desire to break up the "too big to fail" banks. But some would say that the phenomenon of the "Bernie Bros" shows another, uglier side of Sandersite populism. In short, the Bernie Bros are the Sanders supporters who make ad feminam attacks on Hillary Clinton and her feminist supporters online. Bernie Bros presumably oppose anyone who appears to support Clinton because she is a woman, and despise the argument that Clinton's gender is a significant "progressive" credential. That their opposition sometimes takes an ad feminam turn is unsurprising. It's almost impossible to argue against feminist voting priorities without appearing misogynist to many observers, but there's also ample evidence that some attacks by presumed Bernie Bros on Clinton or her supporters are misogynist in fact. It doesn't follow, however, that an anti-feminist attack on Clinton supporters is automatically misogynist, any more than it's impossible for anyone to think Clinton the better candidate on the issues. I don't think it's misogynist to argue that electing the first woman president needn't be the Democratic party's highest priority this year. Also, and as I've written before, the Democratic race would have a much different tone, with a lot less ad feminam or ad hominem argument, were Senator Warren running against Sanders in Clinton's place. Furthermore, let's make a distinction between ad feminam and ad hominem criticism of Clinton herself. Her character is definitely open to question without her gender coming into it, and anyone who interprets any ad hominem attack on Clinton as misogynist is probably sexist herself.
With all that being said, it's still unsurprising that some left-wing strains of populism bristle at any feminist argument in Clinton's favor. Populists in many cases are simply the left-wing or otherwise unorthodox versions of the proverbial angry white male -- the ones who for whatever reason don't buy into the Republican party and its ideology. Just as populists in general identify themselves in all their particularity with "the people," so the white male left-wing populist or "Bernie Bro" may see his problems and concerns as those of humanity in general, or at least the nation, while concerns raised by those who are obviously different by virtue of gender, sexual preference or race are minority or "special" interests of self-evidently lesser priority. He's tempted to question whether advances against exclusion for "minorities" are advances for humanity or the nation as a whole rather than specific advances, of limited general benefit, for women, gays, other races, etc. This may result from a vestigial Marxism according to which class is all, with class visualized according to white male specs, or it may be simple resentment of others getting (or even demanding) political attention while he appears to be ignored precisely because he is the "ordinary" or "normal" citizen. In any event, he isn't really any less narcissist than women or non-whites; it's just his "privilege," if you will, to be able to see himself as the generic human being in a way that his very assertion has historically made more difficult for other people. Again, while this tendency becomes exaggerated when the subject is Hillary Clinton, it shouldn't be overstated. Many Bernie Bros might well ditch Sanders for Warren in a heartbeat, were the opportunity to arise, if only because, to keep things superficial, Warren is considerably younger than Sanders or Clinton. However, if Warren's turn does come, and Clinton's quest has failed, there probably still will be some resentment of women making much of Warren becoming the first woman President.
Until the thing happens, there will always be a gap of perception and affection when women run for President, with "meritocratic" objections raised against "making history" as an end unto itself, and the skeptics' meritocratic objections to making history subject to skepticism. Few will want to wait until every potential Bernie Bro is convinced that the woman in the field is the best possible candidate, since some will think some Bros biased against ever believing that. In the best case scenario, the qualitative difference between candidates should be so slight that primary voters should be willing to risk making history and thus getting that part of history over with. In the present case, however, the qualitative difference between Democratic candidates seems far from slight, and if some seek to paper over that difference in order to make history, they shouldn't be surprised if others resent the attempt. But perhaps we should blame Senator Warren for all of this. Had she, rather than Sanders, challenged Clinton this year, Clinton would have been unable to play the gender card, and we most likely wouldn't be raising this topic at all.