Bernie Sanders in Manhattan View Full Caption

MORNINGSIDE HEIGHTS — Sen. Bernie Sanders appeared before a sold-out crowd at Riverside Church Monday night to tell the Democratic Party, "I told you so" in an area that overwhelmingly rejected his bid for president.

“Not everybody, especially my colleagues in Washington, are happy to hear this. It wasn’t that Trump won the election. It was that the Democratic Party lost the election,” he told over 1,000 people Monday night at an event to promote his new book inside the church on 120th Street and Riverside Drive.

Progressive ideas like universal health care, addressing wage inequality and raising the minimum wage won Sanders primary voters all over the country, especially in states Hillary Clinton ended up losing to Trump.

But those issues didn’t win over many Upper Manhattan voters.

Clinton won every single voting precinct in Harlem, the Upper East Side and the Upper West Side, losing only a handful in Hamilton Heights, East Harlem and Morningside Heights, according to election results.

Sanders dismissed the notion that Trump voters are all right-wing extremists, saying it was dangerous to focus on that point.

"It is a mistake, a serious mistake in my view, to believe that all Trump supporters are racist or sexists or homophobes," he said. "If you think that, you are missing the major point."

The Democratic Party's message didn't resonate with working-class Americans, and Trump told those same voters he would help them while the Dems abandoned them, Sanders said.

Sanders was nonetheless well received by fans for his new book, "Bernie Sanders Guide to Political Revolution," a how-to-guide for young progressives.

The sold-out crowd booed when Sanders mentioned Trump, applauded when he mentioned the evils of income inequality and gave him a standing ovation when he said the Democrats handed Trump the election.

Many of them wore "Sanders 2020" buttons and shirts that read “Hindsight is 2020.” One even brought a bust of the Vermont senator.

Shaun Moran, Sanders’ self-described "biggest fan," wrapped the bust in a powder-blue blanket to protect it during his two-hour bus ride from New Jersey. He paid $300 for the bust, which he bought in a store that also busts of Barack Obama, Walter White and The Dude from "The Big Lebowski."

Like many in the audience, Moran felt the Democratic Party sold out his candidate.

“He lost because the DNC never really rooted for him,” said Moran, a 24-year-old college student.

Sanders said he hopes his book helps young progressive channel their passion and energy into political action.

"What this book is about is a need for a political revolution in this country," he said. "What it’s about is the need to transform — it’s not just about winning elections — but what is more important is the need to transform this country economically, politically and socially. And the energy and idealism of young people will play and is playing today an integral goal in making that revolution."