Forget about feeling the Bern. This was an inferno.

More than 7,500 faithful flocked to Sen. Bernie Sanders’ rally on the eve of Tuesday’s New Hampshire primary — foreshadowing a possible high-energy duel between the Democratic socialist and President Trump.

At a packed Whittemore Center Arena at the University of New Hampshire in Durham, the 78-year-old Vermont senator — who leads in most polls for Tuesday’s race — called for a political revolution and vowed that he would win the first-in-the-nation primary and become the next occupant of the White House.

“This turnout tells me why we’re going to win New Hampshire, why we’re going to win the Democratic nomination, and why we’re going to defeat the most dangerous president in the modern history of America,” Sanders said.

Just 30 miles away, President Trump was hosting his own rally in Manchester to an enormous crowd of 12,000 people — the two blockbuster events were strikingly similar as both men, outsiders in their own parties, energized the crowds with their own version of a political revolution.

“Let’s be clear why Donald Trump is coming to New Hampshire on the eve of the primary,” Sanders told his followers. “He’s scared. He recognizes — just like the party establishment and the corporate donor class — that this movement will defeat him,” he said.

The enormous turnout for Sanders, which may have been aided by a performance from rock band The Strokes, indicates that the presidential wannabe will claim victory at Tuesday’s primary after last week’s chaotic Iowa caucus debacle which saw both Sanders and opponent Pete Buttigieg declare they were the winner after the results were delayed for days.

Sanders has consistently drawn the largest crowds in New Hampshire and on Tuesday blew the doors off of the previous record of 1,981 people that he set at a rally in Keene on Sunday night.

On the eve of the New Hampshire primary, a new Quinnipiac poll had Sanders pulling ahead of presumptive frontrunner Joe Biden — snagging 25 percent of the vote among Democratic voters and independents who lean Democratic.

While Sanders refrained from attacking his Democratic opponents, his famous surrogates, including actress and failed New York gubernatorial candidate Cynthia Nixon and firebrand Bronx Congresswoman Alexandria Ocasio-Cortez, took turns at bashing moderate candidates.

“We welcome their hatred,” Ohio state senator and Sanders surrogate Nina Turner told the crowd, referring to an internal Democrat freak-out about the outsider candidate winning the nomination.

“Whose side are you on? Either you are on the side of working day people or you are not,” she said, blasting moderate Democrats.

The crowd wasn’t exactly on their best behavior either — loudly booing Nixon when she mentioned the fact that she supported Hillary Clinton in 2016 and showing a Trumpian disdain for the media, jeering when Nixon accused journalists of peddling anti-Sanders “nonsense.”

“We’re at a crossroads in our democracy,” Ocasio-Cortez told the progressive faithful who gave her a standing ovation as she entered the arena. “This is why we need to nominate someone a political revolution at their back,” she continued.

“One nomination brings us back to business as usual, but business as usual is not working for the working people. We can choose to move forward,” she said.

The groundswell of support for Sanders on the eve of the primary could also signal a fatal blow to fellow progressive standard-bearer Sen. Elizabeth Warren’s ailing White House bid.

In the crowd of the Durham rally was at least one defector from Warren’s campaign.

“I used to volunteer for Elizabeth Warren but there’s only room for one progressive and he’s got the movement,” Ben Meyer, a sophomore at The University of New Hampshire, told the Post.

Thousands of Bernie supporters lined up for hours to get inside the Durham rally while Trump’s faithful also camped out in Manchester in freezing temperatures, showing just how committed each candidate’s bases are.

However, many of the fresh-faced supporters at Sanders’ event were aware that this was their last shot.

“We missed our chance in 2016,” one University of New Hampshire acolyte told the crowd. “This is our last chance to have Bernie Sanders as president.”