Clinton, meanwhile, is pulling out various stops. In particular, she has spent the last few days assailing Sanders for being, in her view, soft on gun control. She is rolling out an endorsement from Transportation Secretary Anthony Foxx in Iowa, and a group of female senators are stumping for her there—as is Lena Dunham. Chelsea Clinton in hitting the road in New Hampshire.

These are the moves of a candidate who looks, if not necessarily worried, at least a little anxious. And for good reason. Clinton still holds a commanding lead in national polling of the Democratic electorate—all but one outlying poll show her with a strong double-digit lead. But the primary isn’t a national one, and that’s her problem. First, there’s Iowa. The NBC poll is closer than other recent surveys—perhaps in part because it draws on likely voters—but the polling tightened since four weeks ago, when Clinton’s comfortable lead stood at nearly 20 points. Clinton famously lost the state’s caucuses to Obama in 2008, the first step in his remarkably toppling of a frontrunner. Sanders argues that he can win the caucuses just as Obama did, by bringing in fresh voters.

Then there’s New Hampshire, where Sanders has always been strong—thanks in part to hailing from neighboring Vermont. In November, Clinton briefly eclipsed him in a few polls there, but has since fallen behind again.

So imagine a scenario in which Sanders emerges from the first two contests 2-0, and Clinton is still looking for her first win. The race heads to Nevada, where Clinton leads and has been organizing for months but Sanders has recently been furiously staffing up, and then to South Carolina, where Clinton leads by, uh, 36 points in the latest poll (which is almost a month old). Next up are several southern states.

The south is generally said to be Clinton’s firewall. The Democratic Party’s strength in the region is black voters, a demographic among whom Sanders has struggled. He is far more inclined to view matters of conflict in terms of class than race. After several tangles with Black Lives Matter early in the race, Sanders admitted he struggled with African American issues and promised to get smart. He hired as his press secretary Symone Sanders (no relation), a young black activist. He’s incorporated a spiel about police brutality and unequal opportunity for people of color into his stump speech. He’s spent more time around Killer Mike than El-P has over the last few months.

It’s unclear how much dent that has made in Clinton’s African American support. Sanders backers can point to the 2008 campaign, and South Carolina in particular, as proof that black voters will abandon Clinton en masse just as soon as she looks like she can’t win. That’s true as far as it goes, but misses several key points. First, she never led Obama by as much as she does Sanders, and he’d pulled even by Christmas. Second, Clinton is unlikely to be hurt by another grievous verbal gaffe by her husband like the one that so damaged her there eight years ago. Third, Sanders won’t benefit from the good feeling of electing a first black president, as Obama did. During that campaign, there was endless questioning of whether Obama was black enough, but no one will raise that question about Sanders.

All of that means that even if Sanders can sweep the first two—or even three, including Nevada—contests, he faces a steep road, but it also shows why the Clinton campaign might start getting concerned. Her situation is somewhat akin to Marco Rubio. Political insiders and gamblers still view Rubio as the best shot for the GOP nomination, even as he trails in early state-level polls. Clinton at least enjoys a national lead, but both are in the position of insisting that they can and will win even if it takes weeks or months to win an actual contest. But donors and backers tend to get very impatient over such a stretch.