With just over one month to go until the New Hampshire primary, a new poll indicates it's a tight race among the top-four Democratic candidates.

According to a Monmouth University New Hampshire poll released Thursday, Pete Buttigieg is leading among registered Democrats and unaffiliated voters likely to participate in the contest with 20% support, but Joe Biden is only one point behind at 19%, Bernie Sanders is at 18% and Elizabeth Warren is at 15% making it essentially a four-way race.

Compared to Monmouth University's New Hampshire poll from September, Buttigieg has gained 10 points while Sanders' support increased 6 points. Warren, meanwhile, dropped 12 points while Biden also saw a decline in support by six points.

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The new poll finds Amy Klobuchar's support on the rise with 6%. Tulsi Gabbard and Tom Steyer were each polling at 4%, Andrew Yang 3%, Michael Bennet at 2% and Cory Booker at 1%.

This comes after CBS News' latest Battleground Tracker found Sanders at 27%, Biden at 25%, Warren at 18% and Buttigieg at 13% as the first choice for nominee in New Hampshire. That polling similarly also hand Klobuchar at 7%.

New Hampshire hosts the first in the nation primary on February 11, just over a week after Iowa holds its Democratic caucuses.

The Monmouth poll has a margin of error of 4.9%.