Hillary Clinton. (Kevin Lamarque/AP)

There's a data point buried deep within the new NBC-Wall Street Journal national poll that makes one thing very clear: People are increasingly concerned about Hillary Clinton's email server — and its repercussions.

Here's the question and the responses.


Two things are worth noting here.

First, not only do a majority of registered voters say "Clinton's use of a private email server" is important to their vote, but a near-majority (49 percent) say so "strongly."

Second, the trend line on the question is, um, not so good for Clinton. The percentage of people saying the email setup is important to their vote has soared from 42 percent in late October to 55 percent. And the "not important" number has dropped from 48 percent to just over one in three. (This makes sense given how much Clinton's email setup has been in the news of late.)

These numbers put lie to the idea — pushed by many Democrats — that "no one" cares about Clinton's decision to set up a private email server and exclusively use it for her electronic communication as secretary of state.  Or that the only people who care are hardcore Republicans who will never vote for Clinton anyway.

Here's a news update: Fifty-five percent of registered voters are not all part of the Republican base. (If they were, the GOP would be in a much better place.) That means that a not-insignificant chunk of people who say Clinton's email setup is important to their vote are more moderate Republicans, independents and even some Democrats.

What does that mean for the 2016 campaign? That Donald Trump should spend lots and lots of time talking about Clinton's emails.  He is already doing some of it with the "Crooked Hillary" label but, because it's Trump, he rarely stays on one topic long enough for it to really sink in.

These numbers suggest that Trump should, at or very near the top of every stump speech he gives, go after Clinton's email setup and why it's indicative of broader problems with how she (and her husband) conduct themselves.  Yes, the story is in the news today.  But it will fade as the FBI investigation moves from being a top-of-the-mind issue it is today.

But there is clearly a major opening here. Consider this: That same NBC-WSJ poll asked whether, in the wake of the email investigation, people believed Clinton had "the right judgment to make a good president or not." Fifty percent said she did not have the right judgment; just 33 percent said she did.

That's a stone-cold winner if you are Trump. The question is whether he can stay on message long enough for him to benefit from the country's deep skepticism about Clinton and her emails.