The poll that came out Tuesday showing Bernie Sanders leading Hillary Clinton by 27 percentage points in New Hampshire was probably an outlier. But the three before that showing him ahead there by an average of 11 points, and the January polls from Iowa that (minus an outlier in Clinton's favor) showing the pair in a virtual tie there, are having much the same effect on Democratic elites as Donald Trump's unexpected staying power is having on their GOP counterparts: It's making them extremely nervous.

Exhibit A is this New York Times story reporting that, after Hillary & Co. have played footsie with Sanders' left-wing positions, the Clinton campaign is now starting the play the "socialist" card against the senator. They're also issuing warnings about Sanders that sound much like what Republicans say about Trump, per this excerpt from the story:

"It is a scenario many Democrats long dismissed as even remotely plausible: the 74-year-old Mr. Sanders, a registered independent who self-identifies as a democratic socialist, as their nominee. But the possibility of his defeating Mrs. Clinton in Iowa and New Hampshire next month has prompted some of her prominent supporters to discuss how they could attack Mr. Sanders if his candidacy began to look less like a threat and more like a runaway train: calling him unelectable and warning Republicans would have a field day if he were the Democratic nominee." (emphasis added)

Exhibit B is this Washington Times story conveying Dems' concerns that Sanders' supporters, again like Trump's backers, could decide to sit out the election if he's not the nominee and they're not sufficiently wooed to show up:

"And they question whether Mrs. Clinton can carry the message of Mr. Sanders, who has cast his campaign as a call for voters to overturn the political order and push back against business and political elites he says are stiffing the vast majority of Americans."

Finally, Exhibit C comes from NBC News , with speculation that the Democratic nominee still might not be Clinton or Sanders, in a way that reminds me of the on-again, off-again "draft Romney" chatter among Republicans:

"If she wins Iowa, Clinton will be set up to separate herself from Bernie Sanders in South Carolina and the March 1 primaries -- after which her campaign can start to focus on the general election. But if she loses Iowa, then, yes, a highly competitive Democratic race will extend into April and May. And that's not all -- panicky Democrats will become even more nervous, Joe Biden's phone will ring, Michael Bloomberg's phone will ring, too."

Biden just happened to mention a couple of weeks ago that he "regret(s)" not running for president "every day," though he also called it "the right decision."

And all of this happened even before Fox News' huge report that some of the emails on Clinton's private server had information that was of a higher classification level than even "top secret."

If nothing else, this is a reminder that fluidity is part and parcel of electoral politics. Today's lead by Trump or surge by Sanders may well be tomorrow's historical footnote, if history is any guide. Just four years ago , Rick Santorum came from nowhere to win Iowa narrowly, nearly quadrupling the level of support he had in the polls just 15 days before the caucuses. It didn't require a collapse of support for the front-runners at this point in that contest: Both Ron Paul and Mitt Romney finished with much the same percentage that they'd received in polls; they simply were surpassed.

But it's also a reminder that the GOP isn't the only party facing a struggle between its base and its establishment -- and that the story of 2016 may end up being even wilder than we've yet guessed.