Hillary Clinton has had one clear mission over the past few months: Move to the ideological left in hopes of shutting down the energy that democratic socialist Bernie Sanders is stirring up among the most liberal end of the Democratic base.

In pursuit of that goal, Clinton flip-flopped on the Trans-Pacific Partnership, a trade deal she once called the "gold standard" but now opposes, and came out in opposition to building the Keystone XL pipeline. She's also worked to be seen as the true heir to the Obama presidency — particularly on issues such as economic inequality and gay rights.

And it's working, according to numbers in a new NBC-Wall Street Journal poll.

Asked to describe Clinton's ideology, 4 in 10 Democratic voters said she was either "very liberal" (14 percent) or "somewhat liberal" (27 percent). That's up 10 points from a June NBC-WSJ poll. Clinton's identification as moderate has consequently dipped. In June, 58 percent of Democrats said she was a moderate; today, that number is 47 percent. (The remainder — 8-9 percent — say Clinton is either very or somewhat conservative.)

That movement in Clinton's "liberal" number is a very good thing for her chances of winning a Democratic primary. Her problem — both in 2008 and at the start of this campaign — is that some element of liberals believed she is not truly one of them even while they largely liked her and thought she would do a good job as president. That lack of communion with Clinton led liberals to flock to Barack Obama in 2008 and, on a much less grand scale, to Sanders this time around.

To be clear, Clinton is never going to do enough — tonally and on policy — to make some liberals happy. But she doesn't need to. The key for Clinton is not to be great for liberals but simply good enough for them so that they don't move en masse to someone like, say, Joe Biden — who, unlike Sanders, could theoretically make a serious challenge to the former secretary of state if the circumstances were right.

Clinton's leftward lurch has been cast — including in this space — as a transparent attempt to court liberals and to snuff out Sanders's chances.  Call it whatever you want. But don't say it's not working.