Senator Bernie Sanders continued his poll surge in New Hampshire, the first primary state, earning 25 per cent support among more than 500 likely Democratic voters surveyed there.

The new CNN/University of New Hampshire poll, which was released Sunday, shows the Democratic socialist earning more support than some of his more establishment Democrat competitors.

The results come a little over two weeks before the state is set to hold the vote for the Democratic nominee they want to take on Donald Trump in November.

Joe Biden, the usual front runner in the Democratic field, fell nearly 10 percentage points behind Sanders with only 16 per cent support.

The crowded competition dropped to 12 candidates earlier this month when New Jersey Senator Cory Booker ended his campaign January 13.

Democratic socialist Bernie Sanders continued his polling surge by earning the top spot in a New Hampshire poll released Monday where he amassed 25 per cent support. New Hampshire is the first primary state

He was able to surpass former Vice President Joe Biden, who is usually the national frontrunner, by 9 percentage points

The top five candidates in the poll have all already qualified for the New Hampshire Democratic debate early next month. Tulsi Gabbard still needs to earn 5 per cent or more in two additional polls to earn a spot on stage

Falling just one percent behind Biden is former South Bend, Indiana Mayor Pete Buttigieg, besting progressive Senator Elizabeth Warren.

While Buttigieg earned 15 per cent support, Warren, who usually falls in the top three candidates in polls, earned 12 per cent support.

Rounding out the top five is Senator Amy Klobuchar with 6 per cent.

Hawaii Representative Tulsi Gabbard and tech entrepreneur Andrew Yang tied for sixth place with 5 per cent each.

The poll, which was conducted January 15-23, was released as candidates continue to campaign hard in the first caucus state of Iowa and first primary state – and at least seven candidates get ready to take stage in New Hampshire earlier next month.

All top five candidates in the recent poll have already qualified to make the debate stage in New Hampshire, and on Sunday, Yang reached the polling and fundraising threshold required to partake after failing to qualify for the Iowa debate.

Gabbard, who didn't make the stage in Iowa earlier this month, is also lacking the polling numbers, and is set to miss her third debate in a row.

So far, she has earned 5 per cent support in national or early state polls, counting the CNN New Hampshire poll, but she needs to earn that or higher in two more polls to earn her spot.

Former South Bend, Indiana Mayor Pete Buttigieg earned the No. 3 spot in the first primary voting state with 15 per cent support – just one percentage point less than Biden

Trump has taken some swipes at Sanders as he continues to earn momentum leading up to the early caucus and primary states' elections – also using it as an opportunity to hit at Biden

Gaining momentum at the right time has historically been key to helping a candidate secure the nomination – so while Biden has held the top spot for much of the campaign, the next few weeks could secure who will clinch the Democratic National Committee's nomination.

The New Hampshire poll also comes just one day after a New York Times/Siena College poll of Iowa voters found Sanders leading with 25 per cent of the likely vote.

Nationally, Biden still appears to be holding a lead, with a Washington Post-ABC poll on Sunday showing Biden and Sanders pulling away from the pack.

The poll had the former vice president at the head with 32 per cent support, followed by Sanders at 23 per cent. But the next closest candidate was Warren with half of that at 12 per cent, and billionaire and former New York City Mayor Michael Bloomberg with 8 per cent.

The latest round of polls confirms earlier results this month that showed Sanders gaining momentum.

A much-watched survey of Iowa voters earlier in January also showed the Vermont senator leading his Democratic rivals.