Mispronouncing her name as "Kamaala", he launched a fusillade of labels – "ultra-liberal", "Left-Lunatic", "Marxist", and "ultra-left" – to brand her ideologically at a rally in Charlotte in North Carolina, a state he carried in the last two elections on Wednesday.

His rally was held indoors in a packed stadium with seating on stands of about 10,000 with another 10,000 or so in temporary seats in the playfield, because of security reasons after the sniper attack at his outdoor rally in Butler, Pennsylvania.

He seemed to not have a bandage on his right ear, which had been injured in the recent assassination attempt.

His speech of 100 minutes was theatre and entertainment for his fervent supporters relying on his showmanship and unabashed hyperbole, sometimes fact-challenged.

The only issue he spoke of that could affect India was to repeat his threat to enact what he called the Trump Reciprocal Tariff Act that would impose retaliatory taxes on countries that impose high customs duties on imports from the US.

In a speech thin on foreign affairs, Trump said he would create an "Iron Dome" missile defence using domestic technology and manufacture.

He also claimed he would end the Ukraine War on Day 1.

He criticised Harris for boycotting Israel's Prime Minister Benjamin Netanyahu's address to Congress earlier in the day.

"She is against the Jewish people," Trump said, ignoring the fact that Harris is married to a Jewish man, Doug Emhoff.

Harris appears to be narrowing Trump's lead in polls, though still within the margin of error, requiring him to reorient his campaign.

RealClear Politics aggregation shows Trump's lead at 1.7 per cent against Harris compared to 3.1 per cent against Biden.

In a preview of the campaign, he focused on the hot-button issues that he could exploit against Harris like immigration, law and order, and transgender men in women's sports, and on issues like abortion rights and his felony conviction that put him on the defensive.

He asserted that she, as the "immigration czar", had allowed in 20 million illegal immigrants, many of them "rapists", "murderers" or insane. (That number is about double the generally accepted number in the 10 million range.)

He mentioned the recent instances of illegal raping and murdering young women and girls.

Because of Harris' policies of extending medical care to illegal immigrants, "low-IQ" people were incentivised to come to the US.

He brought up her earlier statements against the immigration service likening its officers to the racist Ku Klux Klan and against police

One of the key issues that Harris is running on is abortion rights, which the Supreme Court made a state matter, overturning a previous ruling that had allowed abortion nationally.

Democrats count on the abortion issue mobilising women voters to vote against him because the Republican hardliners want to ban abortions.

Trump said that she wanted to permit abortions right to the moment of birth, but going against his party's absolutists, he did not take a stand on a national abortion policy and said it should be decided by states, but added that he wanted it legal in cases of rape, incest, and life of the mother.

He said obliquely that there's an election to be won – in a signal to party members calling for a total ban that abortions, still a volatile issue in the US, could affect his election and required a flexible approach.

Harris has boasted of her past career as a prosecutor and compared that to Trump's conviction on 34 charges of criminal fraud over the accounting for payments made to a porn star who alleged she had an affair with him.

"She is the worst prosecutor," he said, recalling the start of her political career with her election as San Francisco prosecutor, he asserted that the city has become unlivable because of her policies that created the crime epidemic.

She was committing crimes by letting in "bloodthirsty" criminals into the country, he said.

As he turned his searing spotlight away from Biden, Trump asserted that he had been forced to get out of the race by a coterie of "dangerous people" who threatened to oust him by having his cabinet invoke a constitutional provision to remove a president deemed incapacitated.

Branded by Democrats and even his party dissidents as a "threat to democracy", Trump asserted that Harris was the threat because the party had disfranchised the members who had voted in the party elections for Biden by making her the candidate.

But he continued his attacks on Biden calling him the "worst" president in US history.

He called Biden a "fake liberal" and that Harris had been behind his "ultra-liberal" policies.

Biden who spoke from the White House minutes after Trump had ended his speech, did not mention him by name even once but alluded to him several times.

"Do we still believe in honesty, decency, respect, freedom, justice and democracy," Biden asked.

Trump recalled the July 13 assassination attempt and said that when the shots were fired, his audience did not stampede because "they were brave people who love the country".

On domestic policies, he repeated his usual 'mantras' about shutting down the borders, deporting criminals, cutting taxes and ending climate change policies by scrapping mandates for electric vehicles and allowing drilling for oil and fracking for gas.