Something remarkable is happening in American politics. For the first time in our history, a socialist is running a close second and gaining ground on the front-runner in a presidential race.

Anyway you look at it, Senator Bernie Sanders is making history and may very well play a deciding role in who will be the next president. How real is the Sanders movement? Well, at this point in his campaign in 2007, Barack Obama had 180,000 donors on his way to setting records with low-donor contributions; Bernie Sanders has 250,000.

How’s he doing with voters in early states? “The next time Hillary Rodham Clinton visits New Hampshire, she need not look over her shoulder to find Bernie Sanders; the Vermont Senator is running right alongside her in a statistical dead heat for the 2016 Democratic presidential nomination, according to a CNN/WMUR poll,” wrote The New York Times on June 25 .

But lest the Sanders surge in New Hampshire be dismissed as neighboring state advantage, the Clinton campaign seems even more worried about losing Iowa. In a carefully orchestrated bit of expectation lowering, Clinton campaign manager Robby Mook recently said, “the caucuses are always such a tough proving ground” and Clinton campaign spokeswoman Jennifer Palmeri said, “We are worried about [Sanders].”

Here’s what we know has happened so far in the Democratic primary for president. Since Hillary Clinton started spending money, hiring staff and campaigning, she has lost votes. In Iowa and New Hampshire, she was doing better in the polls in January than she is today. Heck, she had more votes last month than she has today.

Politics is about trends and the one thing we know is that trends escalate in speed as elections near. Even starting out with the huge lead that she did, Clinton can’t allow Sanders to keep gaining votes while she loses votes in the hope that the bleeding won’t be fatal in the long run.

So far Clinton’s approach has been to try to demonstrate to the element of the party that finds Sanders so appealing that she is really one of them. This seems like an extremely flawed strategy that plays directly to Sanders’s strengths. If the contest is going to come down to who can be the most pure liberal, the best bet is on the guy who actually is a socialist. Particularly when running against someone with Hillary Clinton’s long record of being everything that the current left of her party hates.

The truth is, Hillary Clinton has supported every U.S. war since Vietnam. She supported not only DOMA, which her husband signed, but a travel ban on those who were HIV positive. She supported welfare cuts (remember her husband’s efforts toward “ending welfare as we know it”?). She supports the death penalty and campaigned in her husband’s place during the 1992 New Hampshire primary when he left to oversee the execution of an African-American man whose suicide attempt left him brain damaged.

And if “mass incarceration” is a problem today, keep in mind she has long advocated for the criminal justice policies that called for locking up more people for longer periods. She supports—and, as Secretary of State, participated in—the U.S. policy of targeted assassinations, including when the targets were American citizens.

In a political environment in which income inequality is a rallying cry, she makes $300K plus expenses an hour. In fact, she would be the wealthiest person elected president in the modern era.

We can debate the merits of each of these positions but it’s hard to argue it’s not exactly the dream résumé for the 2016 progressive candidate. And guess what? The politically active, motivated voters of Iowa and New Hampshire know the difference between someone who got to the White House with a DLC-backed president and a guy who went mainstream when he started calling himself a socialist and not a revolutionary.

Like him or hate him, Bernie Sanders is the real deal. He’s the most left-wing candidate to emerge as a serious threat to a front-runner in modern history and the faithful love him. Will he be the next president? No. But if Bernie Sanders beats Hillary Clinton in Iowa and/or New Hampshire, it is likely to set off a chain reaction that will topple Clinton.

Hillary Clinton’s greatest strength—more than being a woman, more than being a Clinton—is the fact that polls show her consistently beating Republicans. Democrats see her as someone who can hold the White House. If she loses to Bernie in Iowa or New Hampshire, most likely the subsequent polls will show her losing to a handful of top Republicans.

And then what happens? Will the Democratic Party rally around her?

Perhaps. But more likely party voices, with great and solemn regret (masking their deep panic), will begin to say that Hillary had her chance, she fought a good fight, but we can’t lose the White House.

Who would get in? I still think Elizabeth Warren could be drawn in under this scenario. It’s very different to get into a race to challenge the inevitable Hillary Clinton versus getting into a race to save the party from a wounded Hillary Clinton. John Kerry could get in. Who knows? Perhaps Martin O’Malley does emerge as the viable alternative.

So how does Hillary Clinton avoid the danger of this scenario? Easy. She has to win Iowa and New Hampshire. She should win Iowa and New Hampshire, and handily. She’s running against an obscure 73-year-old socialist from a tiny state that has few minorities and little organized labor, two of the longtime power centers in the Democratic Party.

But to beat Sanders, Clinton has to stop trying to be Sanders-lite and get about the business of explaining why he’s wrong and she’s right. That’s how every race is won or lost. She has to lay out the case that Sanders has bad ideas—and most of his are—that will kill jobs and hurt people. She has to run as Hillary Clinton, not some new creation that a bunch of thirtysomething operatives put together as a poli-sci project.

She has been involved in political campaigns for longer than most of her staffers have been alive. Thinking that little tricks like getting an “organizer” to introduce the candidate at a rally will change an image built over four decades in politics is like McDonald’s thinking they can take on Starbucks because they now sell espresso.

One of life’s truths is that we all tend to become more like ourselves the older we get. If you’re marrying someone over 65 with the hope they will change, the odds for success are slim.

Hillary Clinton, who has collected vast fortunes in campaign donations from Wall Street and hasn’t driven a car in over a quarter of a century, can’t win a progressive primary. So if she doesn’t change the terms of the race, she’s going to lose. Again.