Vermont Sen. Bernie Sanders is leading former Vice President Joe Biden in a hypothetical matchup of the 2020 New Hampshire Democratic primary, according to a new survey.

Sanders, who won New Hampshire in his unsuccessful bid to upset Hillary Clinton in the 2016 campaign, maintains stronger support in the state than any other presidential hopeful of his party. That includes party luminaries such as Biden and Massachusetts Sen. Elizabeth Warren, according to the University of New Hampshire's survey.

"Most Democratic primary voters (58 percent) are undecided or could not provide a name when asked in an open-ended question whom they would support," the Granite State Poll found. "Democratic primary voters most recently mentioned Bernie Sanders (14 percent), Joe Biden (five percent), Hillary Clinton (five percent), Elizabeth Warren (four percent), and Joseph Kennedy III (four percent)."

Sanders' support rose when the respondents were provided a list of potential candidates. That question revealed 31 percent support for the self-described socialist, compared to 24 percent for Biden and 13 percent for Warren.

The survey results come as Sanders is planning his second trip to New Hampshire in two months, though he has declined to say if he intends to run and must win reelection in Vermont in 2018.

"It's a no-lose situation for Sanders to continue to visit," University of New Hampshire political science professor Dante Scala told the Concord Monitor. "Even if he has no intention of running in 2020, every time he crosses the New Hampshire border, he automatically will get media coverage for the issues he wishes to discuss, as long as the presidency remains an open question for him."

Sanders has also traveled to Iowa while touting a single-payer health care bill that he hopes will form the basis for Democratic policy the next time the party controls Congress and the White House.