Why Hillary is afraid of Bernie

That an independent, Jewish, Vermont socialist could pose a threat to an experienced frontrunner with nearly universal name recognition and one of the most sophisticated political campaigns in history is astonishing, but the signs are clear: Bernie Sanders is surging – and Hillary Clinton is concerned.

The 73-year-old senator from Vermont came out of left field, literally, and for the Clinton team, has gone from a nuisance to a menace.

"We are worried about him, sure. He will be a serious force for the campaign, and I don’t think that will diminish," said Jennifer Palmieri, Mrs. Clinton's communications director, in a Monday interview with MSNBC's "Morning Joe." "It's to be expected that Sanders would do well in a Democratic primary, and he’s going to do well in Iowa in the Democratic caucus."

With his impassioned attacks on billionaires and corporations, Senator Sanders, an independent who caucuses with the Democrats, has been drawing enthusiastic crowds, like the 10,000 people who came out to hear him speak in Madison, Wisc., last week. He has pledged to raise the minimum wage to $15 per hour, make college tuition-free, and guarantee workers family leave, vacation time, and paid sick leave.

“This grotesque level of [income] inequality is immoral. It is bad economics. It is unsustainable, and it is not what the United States of America is supposed to be about,” Sanders told supporters in Madison.

With that populist platform, he appears to be gaining ground remarkably fast.

According to reports, in May, Clinton led Sanders 60 percent to 15 percent, according to a May Quinnipiac poll. Last week the same poll showed Clinton at 52 percent to Sanders’s 33 percent.

In early primary states, Sanders is doing very well. He's now in a dead heat with Hillary in New Hampshire, where one survey last week showed him within 8 percentage points of Clinton.

And a new Quinnipiac University poll found he doubled his share of Democratic supporters in Iowa in just seven weeks. Of course, it was Iowa that spurned Clinton in 2008 when it chose Barack Obama and John Edwards over her, setting off a losing streak from which the Clinton campaign never recovered.

To be sure, Sanders is still a long shot: He's more than 40 percentage points behind Clinton in most national polls, lags by double digits in Iowa, and is virtually unknown to minority voters. He's got far less money than Clinton, and his socialism may not go over well with many Americans, which is why some observers see Sanders as a summer sensation, a flash in the pan.

Still, though she rarely mentions him by name, there's no doubt that Sanders has put Clinton on the defensive.

"I take a backseat to no one when you look at my record in standing up and fighting for progressive values," Clinton assured a crowd at a Dartmouth College cookout this weekend, including some Sanders supporters.

While Clinton won't mention Sanders by name, her surrogates will: Missouri Sen. Claire McCaskill went on Morning Joe on June 25 to declare that "the media is giving Bernie a pass … they’re not giving the same scrutiny to Bernie that they're certainly giving to Hillary."

"I think we underestimated that Sanders would quickly attract so many Democrats in Iowa who weren’t likely to support Hillary," an anonymous Clinton adviser told the New York Times. "We’re working hard to win [Sanders supporters] over, but, yeah, it’s a real competition there."

Sanders's rise poses a delicate challenge for the Clinton campaign, which is running more to the left in 2016 than it did in 2008.

"Directly challenging the senator on his policies and record could elevate his candidacy, alienate some liberal Democrats and make Mrs. Clinton look anxious," writes the Times.

For Clinton, the worst case scenario would see Sanders creating deep divisions inside the Democratic Party and splintering her support.

But there's a silver lining: the competition will also serve to rev Clinton and her campaign as well as energize her supporters and donors – not to mention put to rest talk of the Democratic primary being nothing more than a coronation ceremony for Clinton.

Whether Sanders is ultimately the boon of Clinton's 2016 run, or its bane, remains to be seen.