Ready for Hillary? The American people aren't quite sure.

A new NBC News/Wall Street Journal poll released Tuesday night shows that being out on the "campaign" trail isn't exactly helping Hillary Clinton's public approval ratings. When she left the State Department in January 2013, an NBC/WSJ had her public approval at 69 percent. By October 2013, as whispers of her future political plans grew louder, her public approval was at 46 percent -- one of the lowest marks she had received to that point.

And the latest poll, conducted at the beginning of her book tour and long after the Hillary 2016 buzz began its monotonous hum, has her public approval at just 44 percent.

The numbers are a case study in what campaigning can do to a public figure's persona. People in the political spotlight — but without the electoral baggage — usually catch a break from the public. That's why Michelle Obama keeps high approval ratings while her husband's dwindle...

... and why Bill Clinton's popularity was reaching new heights in 2012 and beyond.

But as soon as voters sense a whiff of political ambition in those they hold in high esteem, approval often begins to break along more partisan lines. Hence the fact that only 7 percent of self-described Democrats have a negative opinion of Clinton in the latest NBC/WSJ poll and about one out in 10 Republicans have a positive view of her -- off significantly from polling of Clinton's time as secretary of state.

Former U.S. Secretary of State Hillary Clinton, right, waves to people in an outdoor restaurant as she departs following a live interview at the FOX News Channel studio in Washington June 17, 2014. (Jonathan Ernst / REUTERS)

The same thing happened during Clinton's past campaigns. In 1999, her public approval rating was 67 percent, according to Gallup. During her 2000 Senate campaign, public opinion of her plummeted. It started to creep up in the mid-50s, only to fall again during her 2008 presidential campaign.

That is not a coincidence.

Once she was safe in the bureaucracy of the State Department, her public approval ricocheted back to where it was while she was first lady.

Do the lowering approval ratings cripple her chances in a presidential primary if she decides to run? Not necessarily. They are just obeying Newt's Third Law of Election Gravity — an approval rating at rest tends to stay at rest, unless acted upon by presidential campaign gossip — and falling to a place where she'll likely be on par with the rest of the candidates.

Clinton's approval ratings will likely continue a tumultuous rigmarole of tumbling and climbing up until she announces (or doesn't). We're only at the very, very beginning stage of people starting to think about whether they like or fear the idea of another President Clinton. The NBC/WSJ poll also points out that only 38 percent of registered voters said they probably or almost certain they would vote for Clinton. Thirty-seven percent of registered voters say they would definitely oppose a Clinton ticket. Most voters aren't even going to think about the 2014 midterms until September (and it's asking a bit much for people to have fully formed opinions about the next presidential election when we're still closer in time to the one that just happened two years ago).

The only thing we can tell for sure from this poll is that voters aren't sure they're ready for Hillary — but they aren't sure they are not ready, either.

The NBC/WSJ poll was conducted  from June 11 through 15. It surveyed 1,000 adult respondents and has a margin of error of plus or minus 3.1 percentage points.