Fewer than three weeks before voting day, the Democratic Presidential race in Iowa is neck and neck between Bernie Sanders and Hillary Clinton—and that’s quite a feat for Sanders. Photograph by Jae C. Hong / AP

In Iowa on Monday, Senator Bernie Sanders said that his rival Hillary Clinton’s campaign was in serious trouble, and claimed that this explained why she was attacking him on such issues as gun control and health care. “I think a candidate who was originally thought to be the anointed candidate, to be the inevitable candidate, is now locked in a very difficult race,” Sanders told reporters. "Obviously, what people in that scenario do is start attacking. . . . That is not surprising when you have a Clinton campaign that is now in trouble and now understands that they can lose.”

Obviously, Sanders isn’t privy to the minds of Clinton and her top aides. Nonetheless, his analysis makes sense. In the past few days, three new opinion polls have been released in Iowa. They all show Sanders closing what had been a considerable gap between him and Clinton, and two of them show him edging ahead. As recently as the end of last week, the RealClearPolitics poll average, which combines recent surveys, had the former Secretary of State retaining the double-digit lead she held for most of 2016. By Tuesday afternoon, the poll average was showing the race as a virtual tie: Clinton 45.5 per cent; Sanders 45.3 per cent.

Iowa is a quirky state, and, because of the primary calendar, what happens there matters quite a bit. For months now, most of the polls in New Hampshire, which will be the second state to vote, have shown Sanders with a narrow lead. Four of five polls released in the new year confirm this picture, and one of those four, from Monmouth University, shows Sanders fourteen percentage points ahead. If Sanders defeated Clinton in Iowa, he would have an excellent chance of following up with another victory in the Granite State—at which point questions would be raised about Clinton’s electability. She could well answer them by scoring comeback wins in Nevada and South Carolina, which will vote later in February. But, still, the sight of the longtime front-runner losing the first two Democratic votes would be pretty shocking.

Adding to the impression that the contest is now in flux, a new CBS News/New York Times national poll of likely Democratic voters also shows Sanders surging. Last month, this survey put Clinton ahead by twenty percentage points. In its latest iteration, her lead was reduced to seven percentage points. (Clinton is at forty-eight per cent, and Sanders is at forty-one per cent.)

To be sure, the shape of the race could shift again before the Iowa caucus, which will be held on February 1st. In addition to criticizing some aspects of Sanders’s record, Clinton has been laying out more policy proposals, which appear designed to shore up her left flank. On Monday, she pledged to introduce a four-per-cent tax surcharge on people who earn more than five million dollars a year. Such a measure would raise the effective tax rates of high earners, such as hedge-fund managers and private-equity partners, who often exploit tax loopholes that aren’t available to ordinary taxpayers. "It’s outrageous that multi-millionaires and billionaires are allowed to play by a different set of rules than hard-working families, especially when it comes to paying their fair share of taxes,” Clinton said in a statement.

It remains to be seen whether Clinton’s proposal, which a spokesman for Sanders described as “too little too late,” will sway the voters. For now Sanders appears to be the one with the momentum, particularly in Iowa. A Quinnipiac University poll that was released on Tuesday showed him leading Clinton among Iowans likely to participate in the Democratic primary by forty-nine per cent to forty-four per cent. That’s a big turnaround from a Quinnipiac poll carried out in December, which had Clinton in front by eleven points.

A second Iowa poll was also released on Tuesday, by the research firm Public Policy Polling. This one showed Clinton retaining her lead, by forty-six per cent to forty per cent. However, it also showed the race moving in Sanders’s direction. “Clinton is down 6 points from her 52% a month ago, while Sanders is up 6 points from his previous 34% standing,” a press release from P.P.P. said.

Evidently, the shift in voting intentions reflected a rise in positive feelings toward the Vermont Senator, who has been attracting big crowds throughout Iowa. P.P.P. noted that, over the past month, Sanders’s favorability/unfavorability rating “has shot up from a 65/23 spread to now 79/13 so his popularity is clearly growing as the voting nears.” The firm said that Clinton’s score was holding steady, at seventy-two/twenty-two. The pollsters from Quinnipiac University found that Sanders’s rating was a stunning eighty-seven/three, compared with seventy-four/twenty-one for Clinton.

“Sen. Sanders’ surge seems based on the perception by Iowa Democrats that he is a better fit for Iowans,” Peter A. Brown, the assistant director of the Quinnipiac Poll, said in a release. More than ninety per cent of respondents to the survey said that Sanders was honest and trustworthy and that he cared about their needs and problems. Sixty-six per cent of respondents said that Clinton was honest and trustworthy; twenty-nine per cent said she wasn’t. And seventy-six per cent said she cared about their needs and problems.

On the other hand, Clinton outscored Sanders when it came to the leadership qualities and experience needed to be President. Her campaign will also take solace in the fact that, although Sanders scored higher marks on the economy and climate change, Clinton was perceived to be best able to handle foreign policy, terrorism, health care, and guns. She also did well on perceptions of her electability in the Presidential contest: eighty-five per cent of the respondents said that she stood a good chance of defeating the Republican candidate, while sixty-eight per cent said Sanders had a good chance.

The new polls also confirmed the existence of glaring gender and age gaps among likely Democratic voters in Iowa. The Quinnipiac poll suggested that Sanders is leading Clinton among men by a whopping margin: sixty-one per cent to thirty per cent. Among women, the survey showed Clinton ahead by a considerable but somewhat smaller margin: fifty-five per cent to thirty-nine per cent. The P.P.P. poll also showed a considerable gender gap, and demonstrated that Sanders is currently getting the lion's share of young voters, whereas Clinton is more reliant on the elderly. Among likely voters between the ages of eighteen and forty-five, the survey showed Sanders leading by fifty-five per cent to thirty-three per cent. Among seniors, the survey showed Clinton ahead, sixty-four per cent to twenty-six per cent. (The new CBS News/Times poll demonstrates that the age gap isn't confined to Iowa. Among Democratic voters under forty-five, this national survey shows Sanders leading Clinton by a two-to-one margin.)

It is worth remembering that there are sizable margins of error attached to both of these polls. The same applies to two more-recent surveys, from NBC News/Wall Street Journal/Marist College and the American Research Group. Rather than trying to say who is leading, the safest thing to conclude is that, fewer than three weeks before voting day, the Democratic race in Iowa is now neck and neck. A month or two ago, that is about the most Sanders could have hoped for.