Photograph by Corey Hendrickson/Redux

On Thursday, while the political world was focussed on the Supreme Court’s Obamacare ruling, two polls came out showing Bernie Sanders making up ground on Hillary Clinton in New Hampshire and Iowa. In a survey carried out by the University of New Hampshire Survey Center for CNN and the Manchester-based WMUR TV, Clinton was leading Sanders by just eight percentage points: forty-three per cent to thirty-five per cent. Meanwhile, a poll carried out in Iowa for Bloomberg found that Sanders now has the support of about a quarter of likely Democratic voters, by far his strongest showing yet in the state that will be the first to vote in the Democratic primary. “It’s tremendous progress that he is making with voters in the first two states,” Tad Devine, Sanders’s chief political strategist, told Bloomberg’s John McCormick. “It’s something we felt on the ground.”

At this stage, it’s necessary to issue a few qualifiers.

First, it’s not July 4th yet, and there are still seven months until the 2016 primaries begin. At this early stage, opinion polls bounce around quite a bit, and no single survey should be accorded very much weight. Second, Clinton is trouncing Sanders in the national polls. Third, even in the early primary states she still has a big advantage. In Iowa, Sanders has yet to come within twenty-five points of her in any poll, and in New Hampshire a separate Bloomberg survey found that she retains a much bigger lead than the CNN/WMUR survey suggested: twenty-six points. “Clinton remains enormously well-known and well-liked in New Hampshire, a state she won before,” Doug Usher, of Purple Strategies, the research firm that carried out Bloomberg’s New Hampshire poll, said. “She benefits from a gender gap in a primary that will be disproportionately female, and even Sanders’s voters admit Clinton is likely the nominee.”

So there’s no need for panic in the Clinton camp, which has adopted the public position that it expected a competitive primary all along. But for Sanders, and for Democrats who would like an alternative to Clinton, the signs are encouraging. The seventy-three-year-old Vermont senator is clearly enjoying himself, hurtling around the country, drawing large crowds, and promoting his progressive agenda. In the past few days, for instance, he has welcomed Pope Francis’s encyclical on climate change, criticized Congress for granting President Obama fast-track authority to complete the Trans-Pacific Partnership, and reiterated his call to expand Medicare into a national health-care system for everyone.

As Sanders promised when he started out, he isn’t criticizing Clinton directly. But he is seeking to draw a contrast between his clear positions on such issues as trade with his opponent’s nuanced statements. And he’s insisting he’s in it to win. Speaking to David Corn, of Mother Jones, Devine explained that Sanders’s strategy is based on raising enough money—forty or fifty million dollars—to advertise in the early primary states of Iowa, New Hampshire, Nevada, and South Carolina, and he claimed that, thanks to lots of small donations, this strategy is working so far. “I don’t know if we can outright beat her in Iowa and New Hampshire,” Devine said, “but we have a real shot at it in both places.”

That may be stretching things. Still, if Sanders keeps gaining, he will certainly have the capacity to disrupt some of the Clinton campaign’s carefully laid plans. Should they go after Bernie? Should they ignore him? Something in the middle? Up until now, the Clintonites have been running a professional and highly scripted operation that has achieved most of its initial goals, but that sometimes resembles painting by numbers. Clinton has the money, the infrastructure, and the support from other prominent Democrats that Sanders lacks, but the Vermont senator has advantages, too: enthusiasm at the grassroots, the flexibility that comes with being a one-man band, and the ability to position himself as a scrappy underdog and outsider.

“You can make the case that a certain amount of Bernie Sanders’s support is a protest vote, but there’s more to it than that,” J. Ann Selzer, the president of Selzer & Co, which carried out Bloomberg’s poll in Iowa, said. “People like him. They like what he stands for. They like showing up at his events and hearing him say things they believe in.” In short, Sanders is running a classic insurgency campaign. And as many establishment candidates have discovered in the past, running against such an opponent can be an uncomfortable experience.