Obama, Biden and Clintons reunite in Chicago for memorial to civil rights icon Jesse Jackson

Hundreds gathered for a memorial to the activist and two-time presidential candidate, who died at the age of 84 in February.

Barack Obama was the first of the former presidents to speak, paying tribute to a man who “stepped forward again and again and again” to fight for racial and class justice.

The Democrat said: “He was a born leader, an athlete, a talker, he knew how to talk, a star quarterback, student body president.

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"He could have succeeded within the confines that were determined for him and had a successful life.

“But he instinctively understood that individual success meant nothing unless everybody was free".

"So he became inspired by the bus boycotts in Montgomery, led seven black students into the whites-only library, sitting down and getting arrested for reading. Think about that.

"The library closed but then it reopened and when it did it was open to everyone.”

On how Jackson’s activism affected his own life, Obama added: “Because of that path that he had laid, because of his courage, his audacity that two decades later a young Black senator from Chicago’s South Side would even be taken seriously as a candidate for the presidential nomination.”

Jackson was born in Greenville, South Carolina, and rose to prominence in the civil rights era, participating in demonstrations alongside the Rev. Martin Luther King Jr.

His activism spanned decades, including two runs for the Democratic presidential nomination, in 1984 and 1988.

In the first race, he won more than 18 per cent of the primary vote and a handful of primaries and caucuses. Four years later, he won 11 primaries and caucuses.

Announcing his death last month, Jackson's family said: "Our father was a servant leader — not only to our family, but to the oppressed, the voiceless, and the overlooked around the world.

“We shared him with the world, and in return, the world became part of our extended family.

"His unwavering belief in justice, equality, and love uplifted millions, and we ask you to honor his memory by continuing the fight for the values he lived by.”