The US is facing daily assaults on democracy, former President Barack Obama has warned, as he lauded Jesse Jackson for fighting abuses of power at a memorial service for the longtime civil rights activist.
Mr Obama joined former presidents Joe Biden and Bill Clinton, along with former Vice President Kamala Harris, at the public event in Chicago for Jackson, who died last month at the age of 84.
President Donald Trump did not attend because of his schedule, a White House official said.
"Each day, we wake up to some new assault on our democratic institutions, another setback to the idea of the rule of law, an offence to common decency," Mr Obama said.
Mr Obama, other Democratic dignitaries and religious leaders urged hundreds of attendees to honour Jackson, an advocate for voting rights and desegregation, by continuing his fight for equality and justice.
"Each day, we're told by those in high office to fear each other and to turn on each other and that some Americans count more than others and that some don't even count at all," he said to applause.
"We see science and expertise denigrated while ignorance and dishonesty and cruelty and corruption are reaping untold rewards," Mr Obama added.
The White House criticised the former president when asked for a comment on his remarks.
"He is a total disgrace for all the hurt he has caused this country and history will not judge him well," White House spokesman Steven Cheung said.
The memorial at the House of Hope, a 10,000-seat venue on Chicago's South Side, celebrated Jackson with a choir performing gospel songs while attendees stood, clapped and sang along. Some attendees arrived hours before the service and waited outside in a line that wrapped around the arena.
"This man here paved the way for so many other people to be able to make a difference in this world," said Robert Holmes, who was waiting in line.
In addition to the former presidents, former first ladies Jill Biden and Hillary Clinton, who also served as US secretary of state, were present, along with basketball great Isiah Thomas and the Rev Al Sharpton, a prominent civil rights activist.
Speakers called to continue Jackson's fight for racial equality as the Trump administration curbs diversity programs and targets museum and educational content on slavery that it deems "anti-American."
President Trump's declarations have also led to the restoration of monuments honouring the Confederate South.
"We're in a tough spot," Joe Biden said. "We've got an administration that doesn't share the values that we have."
Memorial events for Jackson began in Chicago last week, drawing elected officials, advocates and community members.
Jackson's body also lay in state in South Carolina, where he was born.
An inspirational orator and longtime Chicagoan, Jackson helped lead the nation's civil rights movement after the 1968 assassination of Martin Luther King Jr.
For more than half a century, Jackson worked to dismantle segregationist systems and broaden political participation for Black Americans and other marginalised communities.
"While some proclaim Make America Great Again, Jesse Louis Jackson fought to make America achieve the greatness that she promised but always fell short of," said Fr Michael Pfleger, a Catholic priest in Chicago known for political activism.
Jackson's two presidential campaigns mobilised millions of new voters under the banner of the "Rainbow Coalition," pushing the Democratic Party to address issues affecting working-class Americans, farmers and communities of colour.
Bill Clinton urged attendees to ask what they can do that would match Jackson's accomplishments, while Sharpton criticised efforts to weaken diversity initiatives.
"We've beaten people bigger than Trump," Rev Sharpton told the crowd.
"Leave here with some Jackson fire in you, not just a program book," he added.
