Washington (CNN) Hillary Clinton's sizable lead among Democrats in New Hampshire has been trimmed to single digits as Vermont Sen. Bernie Sanders makes a strong push in a state that narrowly broke Clinton's way in 2008 to keep her campaign alive.

The poll marks a significant tightening of the contest since the May Granite State Poll, which included Elizabeth Warren on its list of candidates. In that poll, Clinton stood at 51%, with Warren at 20% and Sanders at 13%.

Brian Schweitzer: When asked by Time if he would be a better candidate for president than Clinton: "Well, I think so, of course. I think I have a background and a resume that isn't just in government."

Brian Schweitzer: When asked by Time if he would be a better candidate for president than Clinton: "Well, I think so, of course. I think I have a background and a resume that isn't just in government."

Andrew Cuomo (in 2014): "I'm focusing on running for governor. And then I'm going to focus on being the best governor I can be."

Andrew Cuomo (in 2014): "I'm focusing on running for governor. And then I'm going to focus on being the best governor I can be."

Kirsten Gillibrand: The New York senator has said she'll support Hillary Clinton "110 percent."

Kirsten Gillibrand: The New York senator has said she'll support Hillary Clinton "110 percent."

Bernie Sanders: "I haven't made up my final decision and I've got to say a lot of my strongest supporters say, 'Bernie, you've gotta stay out of the damn Democratic Party, run as an Independent."

Bernie Sanders: "I haven't made up my final decision and I've got to say a lot of my strongest supporters say, 'Bernie, you've gotta stay out of the damn Democratic Party, run as an Independent."

Former Rhode Island Governor Lincoln Chafee is a one-time Republican, turned independent, now Democrat and is exploring a run for the presidency. On Hillary Clinton, he told CNN "... anybody who voted for the Iraq War should not be president and certainly should not be leading the Democratic Party."

Former Rhode Island Governor Lincoln Chafee is a one-time Republican, turned independent, now Democrat and is exploring a run for the presidency. On Hillary Clinton, he told CNN "... anybody who voted for the Iraq War should not be president and certainly should not be leading the Democratic Party."

Jerry Brown: "If no one runs and [everyone] says we'll have an absent Democratic nominee, would I rule that out? I mean, that would be a little silly, wouldn't it?"

Jerry Brown: "If no one runs and [everyone] says we'll have an absent Democratic nominee, would I rule that out? I mean, that would be a little silly, wouldn't it?"

Elizabeth Warren: "I'm not running for president....I don't get who writes these headlines or what they're about. I think there's just kind of a pundit world out there."

Elizabeth Warren: "I'm not running for president....I don't get who writes these headlines or what they're about. I think there's just kind of a pundit world out there."

Martin O'Malley: "I've been very encouraged as I travel around the country by a number of people who repeat again and again and again their desire for getting things done again as a country and also for new leadership to get those things done."

Martin O'Malley: "I've been very encouraged as I travel around the country by a number of people who repeat again and again and again their desire for getting things done again as a country and also for new leadership to get those things done."

Joe Biden: "That's a family personal decision that I'm going to make sometime at the end of the summer."

Joe Biden: "That's a family personal decision that I'm going to make sometime at the end of the summer."

Jim Webb: "I look forward to listening and talking with more people in the coming months as I decide whether or not to run."

Jim Webb: "I look forward to listening and talking with more people in the coming months as I decide whether or not to run."

Several shifts in the poll seem to explain much of Sanders' gain. Looking at the demographic breakdown in primary preferences, men, younger voters and liberals appear to have moved broadly toward Sanders in the last month. Among men, 52% backed Clinton in the May survey, that fell to 32% in the new poll, while 47% now support Sanders. Likewise, among liberals, a 51% to 16% Clinton advantage is now a 48% to 41% Sanders edge. And among voters under age 50, Clinton has fallen from majority support to a near even split in the new poll, 37% back Clinton while 39% favor Sanders.

And likely Democratic primary voters are now more apt to see Sanders as the candidate who "best represents the values of Democrats like yourself." Sanders trounces Clinton, with 41% of Democratic primary voters saying Sanders does, to 30% who chose Clinton. In the May poll, 38% said Clinton was tops on this question, with 22% choosing Warren and just 13% picking Sanders.

Sanders has also gained dramatically in favorability ratings among Democrats since May. In the new poll, 66% say they have a favorable view of the Vermont senator, while just 11% hold an unfavorable view. In May, 45% had a favorable view and 11% held an unfavorable one.

And the Vermont Senator also holds a big edge over Clinton as the most empathetic candidate in the field; 45% say he's the one who cares the most about people like you, compared with 24% who pick Clinton on that score.

Clinton's advantages are apparent in voters' preferences on the issues, however. She is more trusted to handle two of the top domestic issues in the race: The economy (37%, compared with 28% who prefer Sanders' approach) and health care (43% Clinton to 27% Sanders).

And the former secretary of state's advantages are larger on matters of foreign affairs. She holds a wide lead as the more trusted candidate to handle both international trade policy (55% say they trust Clinton compared with Sanders' 14%; Biden is at 11% on that one) and terrorism (45% Clinton to 12% Biden and 11% Sanders).

But when it comes to dealing with "big banks and corporations," things are much tighter: 36% trust Sanders compared to 31% who favor Clinton.

More see Clinton as presidential than Sanders, with 38% saying she has the personal characteristics and qualities a president should have, compared with 27% who think Sanders is best representative of those qualities. Further, 56% of Democratic voters say she is the strongest leader in the field. On that question, just 13% say Sanders has the edge.

Still, 28% describe Clinton as the "least honest" candidate in the field. No other candidate is named by more than 5% of likely Democratic primary voters.

Clinton's favorability ratings remain strong and have generally held steady: 74% have a positive impression, 19% a negative one, about the same as in May.

O'Malley makes a small gain here, with his favorable rating climbing from 10% in May to 16% now. The former Maryland governor remains largely unknown, however, with 72% unable to offer an opinion.

One interesting contrast between the two parties in New Hampshire: while 75% of Republicans say they're still trying to make up their minds about who to support, that figure stands at 54% among Democrats, suggesting Democratic support is solidifying more quickly than Republican support.

The CNN/WMUR New Hampshire Primary Poll was conducted by telephone by the University of New Hampshire Survey Center from June 18-24 among 1,010 adult residents of New Hampshire. Of those, 360 said they plan to vote in the Democratic presidential primary. Results among likely Democratic primary voters have a margin of sampling error of plus or minus 5.2 percentage points.