CHICAGO, Aug 23, 2024 (BSS/AFP) - Kamala Harris accepted the Democratic presidential nomination in Chicago on Thursday before a rapturous crowd, pledging a "new way forward" if she beats Republican Donald Trump in November's blockbuster election.

The 59-year-old sought to strike a presidential tone as she delivered a message of unity and opportunity for Americans following one of the most extraordinary turnarounds in US political history.

She lashed out at Trump, accusing him of trying to "take our country" backwards and of cozying up to foreign "tyrants" like Russian President Vladimir Putin.

"On behalf of everyone whose story could only be written in the greatest nation on earth, I accept your nomination to be president of the United States of America," the vice president said to huge cheers.

"I will be a president who unites us around our highest aspirations," she vowed.

The convention became a giant party to celebrate Harris's astonishing ascent from something of a political afterthought to Democratic standard bearer upon President Joe Biden's surprise decision to end his reelection bid.

A sea of waving Stars and Stripes flags and chants of "USA" filled the arena as jubilant Democrats anointed Harris.

She was later joined on stage by her running mate Tim Walz and their families, as they held their arms aloft while 100,000 red, white and blue balloons tumbled from the ceiling.

Country act The Chicks sang a version of "The Star-Spangled Banner" while pop star Pink also performed as the Democrats rolled out a list of celebrity backers.

- 'President for all Americans' -

Harris pledged to be a "president for all Americans" in a bid to reach out to undecided voters.

With the November election, Americans have a "fleeting opportunity to move past the bitterness, cynicism and divisive battles of the past -- a chance to chart a new way forward," she promised.

Harris then took aim at 78-year-old Trump, whose campaign has been upended by having to face a woman two decades younger, rather than the increasingly frail Biden, 81.

"We know what a second Trump term would look like," she said, referring to a right-wing think tank's blueprint for a future Republican government. "It's all laid out in 'Project 2025,' written by his closest advisors, and its sum total is to pull our country back to the past."

She laid out her personal story as a child of a single working mother, and her career as a prosecutor, saying she has the background and experience to serve the country in contrast to Trump who she said only works for himself and "his billionaire friends."

Harris also laid out her stall on key foreign policy issues.

Going further than Biden's rhetoric, she called the scale of suffering of people in Gaza "heartbreaking" and vowed to get a ceasefire deal between Israel and Hamas "done".

Cheers erupted when she vowed "self-determination" for the Palestinian people.

Harris promised to "stand strong" with Ukraine as it fights Russia's invasion and support NATO allies -- again all in stark contrast to Trump's isolationist stance on both issues.

- 'Proud' -

The Democrats have been riding a wave of energy and enthusiasm since Harris took on the mantle from Biden a month ago.

The first Black woman nominee for a major party, Harris has wiped out former president Trump's lead in the polls, drawn enormous crowds and raised record funds.

Now her challenge is to introduce herself to a country is still getting used to the new Democratic candidate.

The torch having well and truly been passed, Biden gave a farewell speech on the first day of the convention and said he had called Harris to wish her luck.

"I am proud to watch my partner Kamala Harris accept our nomination for president. She will be an outstanding president because she is fighting for our future," Biden, who is on holiday in California, said on X.

Yet Democrats will also be trying to temper their hopes, knowing that Harris faces a tough sprint to a nail-biting election on November 5, which as in 2020 may be decided by a handful of votes in key states.

From Barack and Michelle Obama to Bill Clinton, senior figures have warned all week that Harris has a brutal fight on her hands to beat Trump.

Trump is increasingly resorting to personal insults, racially charged attacks, and dark rhetoric.

His campaign described Harris's performance as the "worst speech ever."

And on his Truth Social platform, Trump wrote in his characteristic all-caps style: "SHE HAS LED US INTO A FAILING NATION STATUS!"