After counting nearly 90 percent of the ballots, Sanders, the leader of the progressive wing of the Democratic Party, won with 26 percent of the vote.
Former mayor of South Bend in Indiana, Pete Buttigieg, was slightly behind him, getting 24.4 percent.
Senator Amy Klobuchar, who was hoping for a breakthrough after a successful debate performance on Friday, came in third with 19.7 percent.
“This victory marks the beginning of the end of Donald Trump,” Sanders told cheering supporters after NBC and ABC announced results showing his leadership.
Senator Elizabeth Warren (9.3 percent) and former Vice President Joe Biden (8.4 percent) are well behind the top three.
Anticipating such a disastrous result, Biden left New Hampshire for South Carolina, where the next primaries will be held, even before the first results are announced.
Biden, 77, has run for President twice before, but without success.
In 2008, he won election as Vice President under President Barack Obama. This time, he hopes to stay afloat until the South Carolina primary on February 29 and the vote in several southern States at once in the “Super Tuesday” on March 3, where support from African-Americans should be his advantage.
“It’s not over yet. It’s just beginning,” Biden told supporters in South Carolina.
Shortly after the polls closed in New Hampshire, sources in the campaign headquarters of businessman Andrew Yang said that he had withdrawn his candidacy and was no longer in the presidential race.
Colorado Senator Michael Bennett also stopped campaigning on Tuesday in New Hampshire.
After Yang and Bennett left, the number of candidates, vying for the Democratic nomination dropped to nine.
According to NBC and CBS, Joe Biden and Elizabeth Warren did not get enough votes among New Hampshire residents to win the support of delegates who will vote for a single party candidate at the Democratic National Convention in July.
The winner of the New Hampshire primary can gain an advantage in two other States, Nevada and South Carolina, where voting will take place on February 20 and 29, respectively. This will be followed by a “super Tuesday” when voting will take place in 14 States at once.
The day before the primary in snow-covered New Hampshire, Trump held a rally for his supporters, at which he criticized democratic candidates.
“They are fighting each other, they have turned on each other,” he said. – They don’t know what they’re doing.”
If Sanders ‘ lead persists, he can consolidate his status as the favorite, which, however, will be on the heels of two popular centrists. Many political analysts doubt that a self-proclaimed democratic socialist like Sanders can unseat Republican President Donald Trump.
The current President has repeatedly denounced Sanders ‘ socialist policies, which include access to free health care for all Americans.
Some analysts expect some voters to put the name of former New York mayor Michael Bloomberg on the ballot. Bloomberg was not on the ballot in New Hampshire, choosing to focus on other States where voting will take place in the next month.
However, Bloomberg has recently become the target of Trump’s criticism, indicating that he is beginning to attract attention among other candidates.