These have been amazing days. Donald Trump, wounded in an assassination attempt, recovers and is the supreme hero of the Republican Party, on course to win a return to the presidency. President Joe Biden, against all his personal and political instincts, leaves the field when he finally accepts that he had no path to victory in November.

For Trump, the election is about ensuring that it will always be America First, at home and abroad, in a quest to make America great again. For the Democrats, this election is a replay of 2020: who is the most capable, strongest candidate to defeat Donald Trump and save the Republic?

Four years ago, from a field of over a dozen contenders, Democrats landed on Joe Biden as being the most capable to rid the White House of Trump. Over these past three weeks, with Biden incapable of defeating Trump, there was, contrary to all expectations, the stunning realisation that Kamala Harris was best placed to complete the mission.

All the other potential contenders – especially California governor Gavin Newsom and Michigan’s Gretchen Whitmer – concluded that it was more important to park their aspirations and unite the party to dispatch Trump once and for all. And they did. It was a shock that has electrified tens of millions across the country.

In the debate that ended his political career, Biden was unable to take down Trump on his extremism and unfitness for office. Harris was immediately on the case: “I was a courtroom prosecutor. In those roles, I took on perpetrators of all kinds. Predators who abused women. Fraudsters who ripped off consumers. Cheaters who broke the rules for their own gain. So hear me when I say I know Donald Trump’s type.”

Harris has turbocharged the war chest. She raised more money in the first 48 hours of her candidacy – $US126 million – than Trump raised in all of June. Harris has cut into Trump’s dominance on TikTok – where most younger people get their news – with viral memes from Charli XCX and Katy Perry. Will Taylor Swift, who endorsed Biden in 2020 but has not yet declared, join the party?

But Harris faces a treacherous political landscape.

While Biden boasts about America’s economy being the strongest in the world, three in five Americans believe the country is in recession. Trump enjoys massive support on the two biggest issues that are driving voter sentiment: inflation and immigration. The White House owns the economy. Cost-of-living pressures, inflation and exceedingly high interest rates are taking a toll. Trump beats Harris on who is best to manage the economy by 43 per cent to 29 per cent. On controlling immigration, Trump’s margin is 45-30 per cent.

Harris must turn around the huge lack of enthusiasm voters had for Biden. She has to make up Biden’s lag with young people, Black and Latino voters, and build on support from women on the issue of abortion rights.

There are early signs of quick Harris gains. This week’s New York Times/ Siena poll has Harris narrowing Biden’s gap with Trump, with her approval up from 36 per cent to 46 per cent, and sharp recovery with young voters and Latinos.

Trump’s vice-presidential pick, Senator J.D. Vance, is already pummelling Harris on extremism, race and sex. Trump was into full attack mode this week. He loves denigrating nicknames, and Harris will now be known as “Lyin’ Kamala Harris”, the “most incompetent and far-left vice president in American history”.

Trump said she “has been the ultra-liberal driving force behind every single Biden catastrophe. She is a radical left lunatic who will destroy our country if she ever gets the chance to get into office.” For good measure, Trump smeared her for being Biden’s “border czar” and “the original Marxist”.

Vance is even rougher, and more personal. In a replay of the vicious attacks on Julia Gillard when she was prime minister, Vance has said that women who do not have children are “childless cat ladies who are miserable in their own lives”, with “no direct stake in America."

Republicans in the House are targeting Harris racially. One House Republican called her the “DEI vice president” – the acronym for diversity, equality and inclusion. Another said Democrats support her “because of her ethnic background”. Misogyny and racial slurs never rest. This will get uglier.

Harris has a vice president to pick. She must win the midwestern industrial states that Trump won in 2016 and where Trump is surging – Pennsylvania, Michigan and Wisconsin – to seal victory. Harris may well turn to Josh Shapiro, the popular governor of Pennsylvania.

A Trump-Harris debate will be the ultimate political theatre. Can Trump, who loves bloody, violent pugilism, throw her out of the ring? Can prosecutor Harris convict him of extremism and treason against America’s democracy and bait him into a disqualifying attack?

In this election, is Kamala Harris a retread of Hillary Clinton, whose unpopularity failed to put Trump away? Or is she Barack Obama, the candidate of hope and change, who was able on the night of his election victory in 2008 to talk of “Americans who sent a message to the world that we have never been just a collection of individuals or a collection of red states and blue states. We are, and always will be, the United States of America.”

One hundred days to go until the election. Hell, it’s only the future of the free world.