Speaking to a crowd of buzzing supporters in former President Barack Obama's adopted hometown, Sanders ripped Trump's "incredible hypocrisy" and called the President a demagogue who makes "even a very conservative president like George W. Bush" appealing in comparison.
But it was his unsparing assessment of the party whose nomination he sought in 2016 that set off an audience of nearly 4,000 mostly dedicated "Berniecrats."
"I am often asked by the media and others, 'How did it come about that Donald Trump, the most unpopular presidential candidate in the modern history of our country, won the election?'" he offered teasingly as chants of "Bernie would have won" filled the hall.
"My answer is that Trump didn't win the election, the Democratic Party lost the election," Sanders said, reviving his own past criticisms
It's a line he's used before, but this was a night for the old hits, and Sanders moved through his laundry list of issues over the course of nearly 55 minutes alone on stage before being joined by wife Jane Sanders and RoseAnn DeMoro, the executive director of National Nurses United, the event's union organizers, for a 15-minute question-and-answer session.
Sanders was interrupted repeatedly throughout his remarks by applause and standing ovations, but also by supporters in red waving "Draft Bernie" banners and placards. The group wants Sanders to leave the Democratic mix and form his own "People's Party" ahead of the 2020 elections.
The speech came nearly a year after the final contest in the Democratic primary that launched his "political revolution," and in what many here consider the validating glow
of a British election that saw leftist Jeremy Corbyn's Labour party score massive gains in the UK Parliament.
"They won those seats," Sanders said of Labour, "not by moving to the right, not by becoming more conciliatory -- they won those seats by standing (up) to the ruling class of the UK."
Lamenting Republican control of not just Washington but in state legislatures, Sanders said "the current model and the current strategy of the Democratic Party is an absolute failure."
His prescription for the party was "fundamental change" and to "knock on every damn door" in search of new votes, even in historically inhospitable regions.
"Strong progressives could do far, far better than anyone imagined and ... with proper organization and financial resources we can win in any district in the United States of America," Sanders said, a clear shot at party leaders who have been criticized on the left over a perceived lack of support for upstart congressional candidates in Montana and Kansas.
Sanders also took a series of stinging shots at Trump, labeling him "perhaps the worst and most dangerous president in the history of our country" and a habitual liar.
He argued that the Republican's populist campaign pitch was a deception, a Trojan horse that opened the White House doors to a parade of plutocrats.
"This is a man who ran for president ,,, telling the people of this country that he was going to stand up for the working class, that he was going to stand up to the political establishment and then, once he got elected and without a second's hesitation he brings more billionaires into his administration than any president in history," Sanders said as the audience booed. "And he hires the former president of Goldman Sachs to be his chief economic adviser."
This is the second annual People's Summit, which is again being hosted in the sprawling McCormick Place convention center on Lake Michigan. Sanders did not speak at or attend the June 2016 gathering.
As DeMoro took the stage following his remarks, she looked out and stopped to thank "all the 'Draft Bernie' people."
"I am with you," she said, and crowd erupted again.