Joe Biden speaks at first night of the Democratic national convention

Joe Biden took centre stage for perhaps the last time on Monday night when he addressed the Democratic national convention in Chicago – as the US president faces a backlash over one of his most complex legacies.

Thousands of protesters are converged in the host city earlier in the day to demand that the US end military aid to Israel for its ongoing war in Gaza. Activists have branded Biden “Genocide Joe” and called for the vice-president, Kamala Harris, to change course.

Harris herself made a surprise appearance at the convention Monday night, thanking Biden for his lifetime of service to the country and previewing the week ahead. The crowd in the Chicago’s United Center got on their feet and enthusiastically cheered and chanted.

Biden’s wife Jill and daughter Ashley spoke shortly before the president, speaking of his support for them and his decision to pass the torch to Harris.

“Weeks ago, when I saw him dig deep into his soul and decide to no longer seek re-election and endorse Kamala Harris,” Jill Biden said. “With faith and conviction, Joe knows that our nation’s strength doesn’t come from intimidation or cruelty, it comes from the small acts of kindness that heal deep wounds, from service to the communities that make us who we are, from love of a country that shines with promise and renewal. Kamala Harris knows that too.

Other prominent Democrats took the convention stage, including Hillary Clinton, a former secretary of state who backs Biden’s Gaza policy, and congresswoman Alexandria Ocasio-Cortez, a progressive star who has criticised the administration and called for a ceasefire.

“Something is happening in America. You can feel it,” said Clinton, who was the first female presidential nominee of a major party.

Jamie Raskin, a representative from Maryland who served on the January 6 committee and led Trump’s second impeachment, said reelecting Trump would bring America “back to the days of election suppression and violent insurrection”. He suggested making Harris’ victory so large that even Trump and his allies can’t try to steal the election.

Andy Beshear, the governor of Kentucky who was a vice-presidential contender, focused his speech on Harris and Tim Walz’ support for reproductive rights. Republican abortion “policies give rapists more rights than their victims”, he said. And Senator Raphael Warnock from Georgia spoke about the need to protect democracy, invoking his faith to denounce Trump.

“I saw him holding the Bible, and endorsing a Bible, as if it needed his endorsement. He should try reading it,” Warnock said. “It says, do justice, love kindness and walk humbly with your God. He should try reading it. It says, love your neighbor as yourself.”

Many speakers pointed out the differences between Trump the convicted criminal and Harris the prosecutor. Representative Jasmine Crockett of Texas called Trump a “career criminal”, “fraudster”, and “cheat”, and contrasted him with Harris, who has always worked for the people.

Shawn Fain, president of the United Auto Workers, wore a T-shirt calling Donald Trump a scab during his speech, saying that “this election comes down to one question: which side are you on?”

“On one side we have Kamala Harris and Tim Walz, who have stood shoulder to shoulder with the working class,” he said. “On the other side, we have Trump and Vance, two lap dogs for the billionaire class who only serve themselves. So for us in the labor movement, it’s real simple. Kamala Harris is one of us. She’s a fighter for the working class, and Donald Trump is a scab.”

Lauren Underwood, a 37-year-old representative from Illinois, touted Biden and Harris’s role in helping pull the country out of the coronavirus pandemic, reminding viewers early in the programming Monday that “four years ago, it wasn’t safe to hold a convention like this”.

Democrats this week will dedicate time to highlighting concerns about Project 2025, the blueprint for a potential second Trump administration. A state senator from Michigan, Mallory McMorrow, held up a copy of the policy manual and read from its proposals Monday. “That is not how it works in America,” she said about the plans for Trump to weaponize the department of justice to his advantage. “That’s how it works in dictatorships.”

Women who suffered because of abortion bans in a post-Roe v Wade America or who obtained an abortion shared their stories from the convention stage, saying that Harris will fight for the rights of women and girls.

Just over a month ago Biden had been expecting to give Thursday’s closing speech as he accepted the Democratic nomination for 2024. But his withdrawal from the race last month, and the party’s consolidation around Harris, means that Biden will speak on opening night and then set off on a holiday.

The president has been reportedly working on his address with his long-time adviser Mike Donilon and chief speechwriter Vinay Reddy. He is expected to return to a familiar theme – the defence of democracy against Donald Trump – and tout Harris as the ideal successor.

It will be a bittersweet moment for the 81-year-old, who is still reportedly irked by the role that the senior Democratic figures Barack Obama, Nancy Pelosi and Chuck Schumer played in pressuring him to step aside amid questions about his mental fitness.

Still, the mood among Democrats is buoyant as opinion polls show Harris leading or tied with Trump in crucial swing states. The Illinois governor, JB Pritzker, told CNN’s State of the Union programme that the convention would be “like a rock concert”. Singers Jason Isbell and James Taylor performed Monday.

But the party is eager to avoid any repeat of their Chicago convention in 1968, when anti-Vietnam war protests and a police riot led to scenes of chaos that stunned the nation and contributed to the party’s defeat in November. But the protests in Chicago on Monday have so far been peaceful and smaller than anticipated.

The biggest protest group the Coalition to March on the DNC planned demonstrations for Monday and Thursday to coincide with Biden and Harris’s speeches. Organisers said they expected at least 20,000 activists to demonstrate, including students who protested against the war on college campuses.

The switch at the top of the ticket has given some activists pause but others contend that Harris is part of the Biden administration and so complicit. Her speech on Thursday will be watched closely for signs that she is willing to take a harder line against the Israeli prime minister, Benjamin Netanyahu.

“We need to hear from Vice-President Harris,” said Abbas Alawieh, a national uncommitted organizer and an uncommitted delegate from Michigan. “We need a plan.” Organizers said they needed something concrete to relay back to voters in their communities to convince them to turn out for Harris.

The convention has drawn an estimated 50,000 people to America’s third-biggest city including delegates, activists and journalists. Security is tight, with street closures around the convention centre, while police have undergone de-escalation training.

On the eve of the convention, Democrats released their party platform, a document of more than 90 pages presenting their policy priorities. The platform was voted on by the convention’s platform committee before Biden’s exit and repeatedly refers to his “second term”.

Speaking to the Guardian, former Barack Obama adviser David Axelrod said he saw the race as a dead heat and that the Harris campaign should fight against a sense of complacency in the party.

“Yes it’s largely tied across the battleground and she’s a point or two behind in the sun belt states,” he said. “And given where we were a few weeks ago, that’s a fantastic place to be. This race is now very close.”

On Monday, the convention is focusing on the Biden administration’s policy accomplishments; Tuesday will contrast Trump’s and Harris’s visions for America; Wednesday will emphasise the importance of protecting individual freedoms; Thursday is entitled “For Our Future”, underlined by Harris’s speech.

Trump and his running mate, JD Vance, will spend the week counter-programming the Democratic convention with a tour of battleground states, including Pennsylvania, Michigan, Wisconsin, North Carolina, Arizona and Georgia.

Andrew Roth and Rachel Leingang contributed reporting