MILWAUKEE: An exuberant Kamala Harris whipped up a rapturous crowd Tuesday at her first rally since effectively clinching the Democratic presidential nomination, as she launched fresh attacks on Donald Trump for trying to "take the country backward."

In a stark contrast to outgoing President Joe Biden's often stumbling and low-energy speeches, Vice President Kamala gave a punchy and enthusiastic address that was greeted with cheers at the event in the battleground state of Wisconsin.

Kamala, 59, is injecting fresh hope into the Democratic party, following 81-year-old Biden's stunning exit from the race after a disastrous debate with Trump fueled fears about his age and mental competency.

"Donald Trump wants to take our country backward," Kamala told the crowd in Milwaukee. "Do we want to live in a country of freedom, compassion and rule of law, or a country of chaos, fear and hate?"

Where Biden used to target Trump as a broad threat to democracy, Kamala took a more personal, targeted approach by pointing to her record as a California prosecutor who had dealt with what she said were "predators" and "fraudsters" like the former president and convicted felon.

"So hear me when I say I know Donald Trump's type," she said, echoing comments she made to campaign workers on Monday. "I will proudly put my record against his any day of the week."

Kamala notably focused on abortion, accusing Trump of trying to ban the procedure and saying that "we trust women to make decisions about their own bodies and not have their government tell them what to do."

The pumped-up crowd repeatedly chanted "Kam-a-la" during her speech in Milwaukee, the same city where Trump was crowned Republican nominee at his party's conference just last week.

Trump's campaign has been thrown into turmoil after the Biden departure, which now makes him the oldest ever US presidential candidate. But Trump insisted that Kamala would be "easier" to beat in November than her boss.

Trump, who survived an assassination attempt on July 13, also told reporters he would "absolutely" take part in at least one presidential debate with Kamala.

Kamala - who is the first female, Black and South Asian "veep" in US history and aiming to become the country's first woman president - took just 36 hours to secure enough delegates to be nominated after Biden's withdrawal.

Top Democratic congressional chiefs - Senator Chuck Schumer and House minority leader Hakeem Jeffries - threw their weight behind her in a press conference Tuesday.

Hollywood star George Clooney - who made waves earlier this month as one of the first high-profile Democratic activists to urge Biden to drop his reelection bid - also backed her.

Biden meanwhile returned to the White House after nearly a week in isolation with Covid at his Delaware beach house, during which he made his shock exit announcement.

Biden announced he will deliver a primetime speech from the Oval Office on Wednesday about "what lies ahead."

Asked by reporters what he would say as he arrived back, Biden replied: "Watch and listen. Why don't you wait and hear what I say?"

Biden's doctor said he was now all clear of Covid.

Both he and Kamala are due to meet Israeli Prime Minister Benjamin Netanyahu this week when he visits Washington.

Kamala's official nomination should now come by August 7 in an online vote of delegates nearly two weeks before the celebratory Democratic convention in Chicago.

Support continued to pour in with the United Steelworkers Union and philanthropist Melinda French Gates, the ex-wife of Microsoft co-founder Bill Gates, both endorsing.

Kamala's campaign also announced it had raised US$100 million since her entry into the White House race, with 62 percent of donations coming from first time donors.

A poll released on Tuesday taken after Biden stepped down showed Kamala two points ahead of Trump.

But Kamala has less than four months to prove to US voters that she has what it takes - and she admitted at the Milwaukee rally that there was "hard work" ahead.

 -AFP