Chicago (CBS) — Bernie Sanders kicked off his campaign for the 2020 presidential election this weekend, and stopped in Chicago Sunday for a rally at Navy Pier.

Sanders’ supporters packed Navy Pier’s Festival Hall, chanting “Bernie” as he promised to lead a political revolution.

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“It ain’t Bernie, it is you. It must be you,” he said.

He said the whole point of political revolution is that no one can do it alone. It must be done together, by the millions.

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“Whether it is the struggle against corporate greed, against racism, sexism, homophobia, environmental devastation, or war and militarism; real change never takes place from the top on down, it always takes place from the bottom on up,” he said.

The Vermont senator told the crowd how his time at the University of Chicago helped shape his political career. Sanders graduated from the university in 1964. While in Chicago, he was arrested for resisting arrest during a protest rally against segregation in the city’s public schools.

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At the rally, Sanders pledged to defeat President Donald Trump and transform Washington.