Senator Bernie Sanders leads DNC candidate Hillary Clinton in an NBC/Marist poll that was released on Sunday.

Sanders beat the former secretary of state 41 to 32 percent in New Hampshire, ABC News reports. This is the second poll in which supporters have put Sanders on top of Clinton. Vice President Joe Biden received 16 percent, but he has yet to join the 2016 presidential race.

Clinton is still leading in Iowa. She leads Sanders 38 to 27 percent, while Biden as 20 percent and former Maryland Governor Martin O'Malley received 4 percent.

Meanwhile, Donald Trump is still leading in New Hampshire and Iowa with 28 percent and 29 percent for the GOP presidential race. Trump recently received his highest support from Iowa at 29 percent.

Non-politicians Trump, retired neurosurgeon Ben Carson and former Hewlett Packard CEO Carly Fiorina received an overall 45 percent support in New Hampshire and 56 percent support in Iowa.

Democratic competitors are not attacking each other and making personal jabs like those taken by GOP candidates during the race, Washington Post notes.

Sanders never ran an attack ad on any of his competitors during his time as a politician for nearly 40 years and doesn't plan on starting now.

"You're looking at a candidate who honestly believes that the discussion of the serious issues facing the American people is not only the right thing to do, it's good politics," Sanders said.

"I know the media would like me to attack Hillary Clinton and say all kinds of terrible things and tell the world that I'm the greatest candidate in the history of the world and everybody else running against me is a jerk and terrible, awful people. Nobody believes that stuff," he added.

Sanders credits his success in the polls to his progressive economic and social agenda, while vowing to take on "the billionaire class."

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