(CNN) Sen. Bernie Sanders at a campaign rally on Saturday will deliver some of his most deeply personal remarks since emerging as a national political figure, according to excerpts provided to CNN by a campaign source.

Casting his own family's working class struggles against President Donald Trump's childhood as the son of a wealthy real estate developer, Sanders is expected to tell supporters at Brooklyn College, "I did not have a mom and dad who gave me millions of dollars to build luxury skyscrapers and casinos and country clubs. But I had something more valuable: I had the role model of a father who had unbelievable courage in journeying across an ocean, with no money in his pocket and not knowing a word of English."

Sanders has spoken at times and written occasionally about his youth in Brooklyn, where he was raised in a small, rent-controlled apartment the decade after World War II. But his refusal to weave it more deeply into his campaign message, or address his family history in a political context, has been a source of frustration among some of his allies, who are desperate for the 77-year-old to articulate a fuller picture of his life to voters. Aides say that in a pair of speeches this weekend, the second coming on Sunday night in Chicago -- where he graduated from college and became an activist in the heat of the Civil Rights movement -- that will change.

"I also learned a great deal about immigration as a child because my father came to this country from Poland at the age of 17, without a nickel in his pocket," Sanders, according to prepared remarks, will say on Saturday. "He came to escape the crushing poverty that existed in his community, and to escape widespread anti-Semitism. Needless to say I would not be with you today if he had not made that trip from Poland because virtually his entire family there was wiped out by the Nazis."

Eli Sanders, his father, came to the United States in the early 1920s, eventually marrying Dorothy Glassberg, the daughter of immigrants. They had two children, older brother Larry, who would become a politician in the United Kingdom, and Bernie, who in 2016 became the first self-identified Jewish candidate to win a major party presidential primary when he defeated Hillary Clinton in New Hampshire. Sanders' mother died decades earlier, shortly after her younger son graduated high school.

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