Did you know that there’s a Democratic presidential primary too? Sure, Hillary Clinton maintains a big lead in national polls and has all the endorsements. Sure, she’s almost certainly going to win the nomination. But if I were running the Clinton campaign, I’d still be a little nervous. Clinton’s lead in Iowa isn’t safe; Bernie Sanders could win the caucuses. And with expectations for her as high as they are, a Clinton loss in Iowa (or even an underwhelming win) would cause her campaign a lot of heartache.

Over the past month, Clinton has had a 53 percent to 37 percent advantage over Sanders in Iowa polls. A survey from polling demigod Ann Selzer found Clinton ahead of Sanders 48 percent to 39 percent. Her position is stronger than it was at this point during the 2008 cycle, when she led Barack Obama 30 percent to 24 percent. Still, past campaigns suggest that Clinton’s current lead isn’t necessarily secure.

In the chart below, I’ve plotted Iowa caucus results for each candidate since 1980 (excluding primaries in which an incumbent president was running) against the candidate’s monthly polling average from this point in the campaign:

There is clearly a relationship (just as there is between national primary results and national polls from this same period). But just six of the 12 candidates leading the Iowa polls at this point went on to win the caucuses. Those who led and then lost include Democrat Howard Dean in 2004, Republican Mitt Romney in 2008, Republican Herman Cain in 2012 and, of course, Clinton in 2008. Not only didn’t they win, none came particularly close.

Past campaigns suggest that 95 percent of the time, Clinton’s percentage of the Iowa vote will be between 32 percent and 68 percent. Meanwhile, Sanders could end up with anywhere between 17 percent and 54 percent of the vote. Heck — even Martin O’Malley (remember him?), who’s averaging a measly 4 percent over the past month, could conceivably win up to 25 percent of the vote based on the predictive error of past caucus polls.

Now, I’m not saying that Sanders will win the nomination or that O’Malley will find his way north of 5 percent. But there’s still time for a Sanders upset in Iowa. At the very least, there’s time for him to finish closer to Clinton than current surveys indicate.

If Clinton were to underperform expectations in Iowa, it could easily lead to a loss for her in New Hampshire, which has consistently been Sanders’s strongest state. We know from past campaigns that candidates who underperform in Iowa tend to do worse than expected in New Hampshire, while those who outperform expectations in Iowa tend to also outperform expectations in the Granite State. The ultimate example of this is Democrat Gary Hart’s stunning upset of Walter Mondale in the 1984 New Hampshire primary. Hart’s stronger-than-expected second-place finish in Iowa gave him a lot of positive media coverage and momentum going into New Hampshire.

And Clinton doesn’t have a lot of room for error in New Hampshire. Sanders and she are basically tied there. A polling average over the past month has Clinton up by 1.5 percentage points, while the HuffPost Pollster aggregate gives Sanders a 1.5 percentage point lead. A closer-than-expected finish in Iowa could easily put Sanders over the top in New Hampshire.

You might be thinking, “So what?” Clinton, at this point, has a pretty insurmountable 49 percentage point lead in South Carolina thanks to strong African-American support. A win for Clinton there after losing Iowa and New Hampshire would probably put her back on track to win the nomination.

Indeed, anyone who has been following my writing this year knows that I think Clinton is a near-lock for the Democratic nomination even if she loses the first two states. Still, Clinton probably doesn’t want a lengthy primary season against an opponent who has pulled her further to the left. She wants to pivot toward the center while the Republican race devolves into a possible (metaphorical) fistfight.

Clinton, though, can’t set her eyes on the general election just yet. The Democratic race may not be receiving the attention that the Republican race is, but Clinton’s path to the nomination definitely has the potential to become a little rockier than many believe.

Dhrumil Mehta contributed research.

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