It’s increasingly obvious that the national polling has tightened between Donald Trump and Hillary Clinton in part because Republicans coalesced behind Trump a lot faster than many anticipated (shocking, isn’t it?) while Democrats have yet to unify to the same degree behind Clinton (which isn’t surprising, since the Democratic primaries are not resolved yet).

So a fair amount rides on how the Clinton camp will manage the task of unifying the Democrats after winning the nomination — not to mention on whether Bernie Sanders does his part. But who are the Democrats who she will need to win over?

New data from Post/ABC polling gives us an answer: The Democratic-leaning voters who view Hillary Clinton unfavorably are disproportionately young, male, white, suburban, and independent.

This week’s Post poll found that among Democrats and Dem-leaning independents, Clinton is viewed favorably by 72 percent, and viewed unfavorably by 26 percent. Post polling guru Scott Clement provided me with this breakdown of that data (click to enlarge):

Of those Dem-leaning voters who view Clinton unfavorably, far more are below 30 years old (37 percent) than from any other age group. Marginally more males than females view Clinton unfavorably (52-48), while those who view her favorably are overwhelmingly female (63-37). Those who view her unfavorably are disproportionately white, suburban and moderate (that last one is perhaps surprising, given the constant claims that Clinton struggles with liberals). A larger proportion of those who view her unfavorably are independents (though Democrats still make up the larger share of that group).

Not surprisingly, a lot of this overlaps with support for Sanders. In our polling, some 87 percent of Dems and Dem-leaning independents who view Clinton unfavorably say they prefer Sanders to her as the nominee. Meanwhile, of Sanders supporters, 53 percent view Clinton negatively, versus 47 percent who view her positively.

The question of whether Clinton can win over Sanders supporters could have real consequences. Nate Cohn averaged together some of the most recent polls and concluded:

The most recent wave of national surveys shows Mrs. Clinton winning just 55 to 72 percent of Mr. Sanders’s supporters….
The good news for Mrs. Clinton is that there’s a lot of room for improvement. She could make gains after winning the nomination, much as Mr. Trump already has. That could leave her with a considerable advantage….
What’s clear is that Mrs. Clinton’s challenge isn’t totally superficial.

Cohn’s crunching of all these recent polls also finds that Clinton is doing far worse among young voters than you might expect.

It probably isn’t an accident, given all this polling, that in recent days, Clinton has taken to saying that she wants Sanders supporters to have a voice at the convention, and has even said she hopes Sanders supporters will play a role in her governing coalition. Meanwhile, the Democratic Party has now made some concessions designed to give Sanders and his loyalists more sway over the party platform.

The most likely explanation for all of this is that Clinton and her advisers — and leading figures in the Democratic Party — know that Clinton will have to work hard to win over Sanders supporters. She and her advisers have repeatedly said as much, and all indications are that they mean it.

There is still plenty of room for things to get very contentious — it’s unclear how the negotiations over the platform will go, and there are some upcoming state conventions, including one this Saturday in Wyoming, where repeats of what happened in Nevada are possible. If this happens, Clinton’s campaign will very likely want the national party to do all it can to dial down the tensions, not up.

It seems obvious at this point that Clinton and her advisers are not taking Dem unity for granted, and are well aware of how much is riding on it. And, of course, if things go well, it could translate into a larger lead over Trump in national polling. Let’s see where we are in late June and early July.