In the years since, Sanders returned to the state often. He maintained a strong volunteer team and a local steering committee that met regularly. His son even ran for Congress in the state last year.

After all, in 2016, no state was better for Sanders than New Hampshire. The independent senator won the first-in-the-nation primary with 60 percent of the vote. The 22-point win over Hillary Clinton — who had a decades-long relationship with New Hampshire — was the biggest victory margin in that state for a competitive Democratic primary in over a half century.

Bernie Sanders and his aides would be forgiven if, when mapping out his 2020 presidential campaign, they didn’t spend a lot of time wondering how the Vermont senator would win the New Hampshire Democratic primary.


But now, with a little more than six months to go until the 2020 New Hampshire primary, Sanders can no longer take the state for granted. He has gone from being the unquestioned front-runner to second place — and sliding.

A University of New Hampshire Survey Center/CNN poll out last week found Sanders dropping 11 points among likely Democratic primary voters since April. He relinquished first place to former vice president Joe Biden and was tied with Senator Elizabeth Warren of Massachusetts. And while Sanders dropped there, Warren has surged by 14 points.

“His campaign supporters felt they had New Hampshire in the bag and they could run this national campaign and dare others to catch up, but here they are in the summer and they are suddenly tumbling in what should be their best early state,” said Wayne Lesperance, a political science professor at New England College in Henniker, N.H. “And if he doesn’t win here, where can he actually go after that?”

At this point, it’s anyone’s guess who, among a handful of candidates, is best positioned to win.


“I think at the end of the day, we’re going to win New Hampshire,” Sanders told WMUR, a New Hampshire television station, on Thursday.

“I’m not here to tell you that it will not be a hard-fought race and a tough race. But I believe we’re going to win it.”

Adam Huberty, who was a senior New Hampshire staffer for Sanders in 2016, still backs Sanders, but said, “I think it is fair to say the staff didn’t think that Warren would be this big of a threat.

She has momentum here, and while she has her own challenges, she is a real problem for Bernie.”

The UNH poll suggests that in the past few months, Warren has become more interesting to New Hampshire Democrats, particularly women in the southern part of the state. Sanders is better positioned with men in the north.

In the poll, Sanders and Warren were tied as the most popular candidates in the field, with 67 percent favorability for each. Biden was at 57 percent.

With 25 candidates in the field, it will probably be impossible for anyone to blow out either New Hampshire or the first caucus in Iowa. There are also several candidates running on key Sanders issues, including supporting free college and a Medicare-for-all-health care plan.

Former New Hampshire state senator Burt Cohen served as one of the 16 Sanders delegates from New Hampshire to the Democratic National Convention in 2016. But in the 2020 contest, he is so far undecided.


“I love what Bernie Sanders says, and I love that so many other candidates are running with his message this time. But it also means that I, like a lot of Sanders backers last time, are still sorting out our choices,” said Cohen, who earlier in July hosted a house party for candidate Marianne Williamson.

The UNH poll found that Sanders is still seen as the most progressive candidate and that he and Biden are seen to have the best chance of winning, though Warren has improved in that category. Sanders, who last campaigned in the state on June 30, also has a large volunteer base there, and this past weekend his campaign held a series of organizing events with them.

Senator Michael Bennet of Colorado, who is also running for president, believes that as voters become more familiar with other candidates, they see there are better options than Sanders.

“He ran for office last time, and he didn’t get a lot of pushback. Essentially he had a free pass,” Bennet said in an interview with the Globe. “And now there is pushback on ideas like Medicare for all that sound interesting but the vast majority of Democrats don’t support and believe will sink us as a party if we ran on it.”

Mark Longabaugh was a senior strategist with Sanders in 2016 and helped map a 2020 strategy before parting ways with Sanders earlier in the year. He contends that Sanders has a lot of advantages, particularly with his volunteer base.


“No, New Hampshire is not just Bernie’s to lose anymore. No, it is not even a contest between just Bernie and Biden, because both are slipping. It is a contest now between four or five of them. Does Bernie have to win in New Hampshire? Well, here is the thing: All of them do.”

James Pindell can be reached at james.pindell@globe.com. Follow him on Twitter @jamespindell or subscribe to his Ground Game newsletter on politics:http://pages.email. bostonglobe.com/GroundGameSignUp