Democratic presidential candidates debate in New Hampshire

Bernie Sanders, left, and Hillary Clinton speak during an exchange during the Democratic presidential primary debate Saturday, Dec. 19, 2015, at Saint Anselm College in Manchester, N.H. (AP Photo/Jim Cole)

Despite holding commanding leads over other 2016 Democratic presidential candidates in an array of national polls, Hillary Clinton is essentially tied with U.S. Sen. Bernie Sanders, I-Vt., in New Hampshire, a survey released this week found.

The former first lady, whose campaign has struggled to win over voters in the first-in-the-nation-primary state, holds a slight 47 to 44 percent lead over the Vermont senator among likely New Hampshire Democratic primary participants, according to a new Public Policy Polling survey.

Due to the poll's plus or minus 4.5 percent margin of error, however, the two Democrats are largely neck-and-neck with just one month left before New Hampshire residents hit the voting booth.

"Hillary Clinton and Bernie Sanders have been within two to three points of each other on our last two New Hampshire polls," said PPP President Dean Debnam. "Clinton is dominant with the Democratic establishment, but Sanders is proving to be more appealing to people outside the party."

According to the poll, Clinton leads Sanders by a 55 to 36 percent margin among Democrats, but the Vermont senator holds a 59 to 29 percent advantage among non-Democrats who plan to vote in the upcoming primary.

Debnam contended that the New Hampshire primary may come down to how many non-Democrats Sanders "can get to come out and choose to vote in the Democratic race rather than the Republican one that's drawn a lot more interest."

Clinton previously trailed Sanders among New Hampshire voters by a 42 to 35 percent margin in August before seeing support surge to 41 percent in mid-October, according to PPP poll results.

Former Maryland Gov. Martin O'Malley, meanwhile, continued to lag far behind his two Democratic opponents, pulling in just 3 percent of the vote, the poll found.

The poll surveyed 480 likely New Hampshire Democratic primary voters from Jan. 4 to 6.