There are a number of ways that the Democratic party is split demographically in the race to pick a nominee. Hillary Clinton gets more support from older voters; Bernie Sanders gets more support from younger ones. Clinton is preferred by those who identify as Democrats; Sanders by those who call themselves independents. Clinton is more strongly supported by women and black voters, too, according to exit poll data compiled by Edison Media Research. Among men and white voters, she and Sanders run fairly even, on average.
But if we dip into the data a little further, we see that there's more to the story. One of the groups that votes against Hillary Clinton most consistently is white men. In 20 of 23 contests for which we have exit poll data, white men have preferred Sanders to Clinton. (The three exceptions were Alabama, Arkansas and Tennessee, all states where Clinton did very well.) In Vermont, Sanders saw one of his most dominant demographic performances: White men in the state favored him by 83 percentage points over Clinton.
If we take six demographic groups -- men, women, whites, blacks, white men and white women -- and arrange them from most-to-least supportive of Sanders, the pattern is clear.
What's interesting is that a similar pattern holds in 2008 exit poll data.
That year, Hillary Clinton lost the nomination to Barack Obama. While she has the overwhelming support of black voters this year, that wasn't the case eight years ago. She had more support from white voters that year, so she had more support from white men, too. But if we plot the data in the same way, this time from most-to-least support for Clinton, you can see that support from men is at the tail end of her support from white voters.
We can look at it another way. In 2016, white men are the only gender-race combination to overwhelmingly favor Sanders over Clinton. White men back Sanders by 26.4 percentage points more than do white women (who prefer Clinton, on average). In 2008, white men voted more for Clinton than Obama -- but were 20.6 points less supportive of her than white women.
In 2016, that lower level of support from white men hasn't hurt Clinton as much as it did eight years ago -- thanks to her support from black voters. But it makes pretty clear that in November, no matter how poorly Donald Trump may do with demographic groups overall (as current polling suggests), white male voters overall remain unlikely to give a majority of their support to Clinton.