Biden hails Harris as torchbearer for democrats in DNC speech

President Joe Biden cemented the Democratic Party's embrace of Vice President Kamala Harris as its leader in the fight for the White House against Republican Donald Trump with a convention speech on Monday. 

Biden took centre stage on opening night of the Democratic National Convention, on Monday, drawing an extended standing ovation from the party faithful, who have swiftly moved on without him.

Wiping away tears after being introduced by his daughter Ashley and waving to the crowd that held signs saying, "We (heart) Biden," a smiling Biden said: "I love you."

"Are you ready to vote for freedom? Are you ready to vote for democracy and for America? Let me ask you, are you ready to elect Kamala Harris and Tim Walz?" Biden said.

Biden's address in Chicago kicked off a four-day event fuelled by enthusiasm for Harris and relief that Biden abandoned his own reelection bid and endorsed her to replace him.

The president's reluctant decision to step aside on July 21 came after heavy pressure from party leaders who worried the 81-year-old incumbent was too old to win or serve another four years.

Biden, who served as No 2 to the nation's first Black president, Barack Obama, is now urging Democrats to unite behind a candidate who, if triumphant on November 5, would become the first woman, who is also Black and South Asian, to be elected US president.

The party's chances of winning have improved dramatically with Harris' candidacy, based on opinion polls, fundraising and the sizable crowds she has attracted.

Instead of his hoped-for high-profile speech on Thursday to accept the Democratic nomination for another four-year term, Biden was the main event at the start of the Chicago convention on Monday before traveling to California for a vacation.

In his speech, Biden touted his administration's accomplishments — boosting the US economy and strengthening US alliances abroad — and made the case for Americans to elect Harris as his White House successor.

He condemned the racism and white supremacy that continue to plague America, saying they had no place in the nation.

Earlier in the evening, the 59-year-old vice president made a surprise appearance, drawing cheers from the crowd as she vowed to defeat her Republican rival Donald Trump, 78, in the November 5 election.

Harris, 59, will formally accept the nomination on Thursday.

"Let us fight for the ideals we hold dear and let us always remember, when we fight we win!" Harris said to the roar of the crowd.

Harris is riding a historic whirlwind into the convention: her campaign has broken fundraising records, packed arenas with supporters, and turned opinion polls in some battleground states in Democrats' favour.

Biden dropped his reelection bid after his disastrous debate performance against Trump on June 27 prompted longtime allies, major donors and other party supporters to demand he step aside.

Polls a month ago showed Trump with a clear lead over Biden, but Harris has closed the gap both nationally and in many of the highly competitive states, including Pennsylvania, that will play a decisive role in the election.

Additionally, protesters against Israel's war in Gaza briefly breached the outer security fence of the DNC in Chicago.

Biden did not directly address the security lapse in his hour-long speech, but he said "those protesters out in the street, they have a point. A lot of innocent people are being killed, on both sides" of the Israel-Hamas conflict.

A small group of around 100 demonstrators broke off from a larger march involving thousands of people and targeted the metal barriers surrounding the gathering.

Police in blue helmets with shields and carrying black batons prevented them from getting to the inner cordon. One demonstrator clad in black was carried out by their arms and legs by several officers, according to AFP.