After three weeks of pained debates in the media and within the Biden administration itself, the 61% of Americans who wanted Joe Biden to step aside have had their wish granted.

Only a few minutes after announcing he would no longer be seeking re-election, Biden made clear he endorsed Vice President Kamala Harris to succeed him, while major Democratic Party stalwarts – including the Congressional Black Caucus as well as Bill and Hillary Clinton, though notably not Barack Obama – quickly followed suit.

Democratic National Committee Chair Jaime Harrison has promised a “transparent and orderly process” to select Biden’s successor, though further details have yet to be made available.

Regardless, the significant endorsements for Harris’ candidacy – combined with the Democratic fear of weakening a presumed nominee in the face of what they deem to be an existential threat in Donald Trump’s candidacy – makes Harris the most likely to be the next presidential nominee.

Who is Kamala Harris?

Harris’s ascent from the first Black woman and Asian American to be vice president to now likely to be the first to lead a major party ticket is historic, to say the least.

The daughter of immigrants from India and Jamaica, Harris began her career as a prosecutor, spending almost three decades in law enforcement. She started as a local prosecutor, then became district attorney of San Francisco before being elected California attorney-general in 2011. Her 2003 district attorney race saw her win more votes than any other candidate running for a city-wide office that year in her defeat of a two-term incumbent.

Her first run for statewide office in 2010 was not called until weeks after election day, and Harris won by less than a percentage point (but was against a favourite).

To this day, Harris has never lost a general election, including her Senate run in 2017. Only the second ever Black woman elected to the US Senate, Harris won her seat under unique circumstances: for the first time since California began voting directly for seats in 1914, no Republican placed in the state’s electoral runoff for the Senate seat. In other words, Harris only had to defeat another Democratic candidate to win.

Senate stint, first electoral loss

Once in the Senate, Harris was appointed to the homeland security and intelligence committees and later the Senate Judiciary Committee, which gave her a platform to grill Trump’s judicial nominees. Whether it be questioning then-Supreme Court nominee Brett Kavanaugh on whether the government had ever made laws related to the male body, or the Mueller investigation’s of the Trump campaign’s collusion with Russia, Harris became known for using her prosecutorial experience to advance Democratic priorities.

Yet as much as some of her Senate performances became well-known among political pundits, her most well-known moment in the national spotlight was before being elected vice president. And it was at Biden’s expense during her campaign to be the Democratic presidential nominee in 2020.

She had already caught the country’s attention with a heavily publicised launch in Oakland, California – this was near where she was born, her parents had worked and she had worked as a district attorney. But at the first Democratic Party debate, Harris directly targeted the then-former vice president, criticising Biden for positive comments he had made about pro-segregation politicians with whom he had served in his 36 years in the US Senate.

While Biden had long postured that his willingness to work with diverse politicians was a political and legislative strength, Harris countered that: “You also worked with them to oppose bussing. And, you know, there was a little girl in California who was part of the second class to integrate her public schools, and she was bussed to school every day. And that little girl was me.”

As compelling as her launch and debate performance was, Harris’s 2020 presidential campaign was widely reported to be beset with disorganisation and the absence of compelling policy proposals. Sliding polls and funding numbers led to her suspending her campaign months before the Iowa caucuses, and long before a single vote was cast in Democratic primaries.

Nonetheless, her viral debate performance established her as a formidable politician and debate opponent – such skills were particularly well-reviewed when she deployed them against then vice president Mike Pence in their 2020 debate.

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Biden’s vice president

While Harris vacated her Californian senate seat after assuming vice presidential duties in 2021, a Senate split 50-50 between Democrats and Republicans saw Harris spend much of her first two years in office back with her Senate colleagues as a decisive tiebreaker on key legislation supported by the Biden-Harris administration.

But outside of her senatorial duties, Biden decided to give Harris a few key portfolios to carry out. This most notably included immigration – a particularly challenging issue that remains a key electoral weakness for Democratic candidates across the country. That the issue remains challenging is telling of Harris’ performance. She has been widely criticised for her ineffective efforts trying to address the “root causes” of the record-breaking immigration influx into the United States.

Harris has found more success in championing other political causes, most notably in relation to abortion. An issue that Biden, a practising Catholic, notoriously felt uncomfortable with, Harris in many ways led the administration’s efforts on the topic after the Supreme Court in 2022 overturned the Roe v Wade ruling that had legalised abortion for decades beforehand.

Lingering concerns

The Democratic embrace of the vice president has not come without concern.

After his first nine months in office – and most notably, the controversial US pullout from Afghanistan in September 2021 – Biden’s approval ratings never eclipsed 45%. While Democrats in the 2022 midterm elections fared far better than predicted and continued to outperform Republicans in special elections around the country, Biden’s approval rating has generally only trended in one direction. This was particularly so after his June 27 debate performance.

As low as Biden’s ratings sank in the three and a half years prior to June 27, Harris’ approval ratings consistently fared worse, making her one of the least popular vice presidents in US history. Over the past year alone, her approval rating has fallen from an average of around 41% in July 2023 to around 38% in June and July 2024.

Yet polling released in July 2024 indicated, for the first time, that she eclipsed Biden (now at 38%) in approval ratings. Most importantly for Democrats, polling in key swing states also indicated she would likely fare significantly better at the top of the Democratic ticket than Biden against Trump. In other words, Harris is the heir apparent to Biden not because she started looking better, but because Biden kept looking worse.

Challenging road

On many fronts, the road ahead for Harris remains uncertain. While the office of the vice president is often perceived as a stepping stone to the presidency, Biden, George HW Bush, and Richard Nixon are the only former vice presidents to have successfully won office through an election in nearly a century and a half. A total of 17 vice presidents have sought the office but only five have succeeded.

Harris will soon name her own vice presidential running mate – widely anticipated to be a moderate male figure who will be used to reassure voters concerned that she is more progressive than Biden. The effort to reassure sceptical conservative voters will also see her likely regularly referring to her many years as a “top cop” should she end up winning the Democratic nomination.

While Harris does not have an official lock on the nomination, her hours-old campaign will certainly make it look like she does. Similar to how the now-suspended Biden campaign fought off the prospect of intra-party challengers in the 2024 Democratic primaries, the Harris campaign will portray Democratic resistance to her as not only futile but also unnecessarily damaging to the candidate ahead of the general election against Trump.

Should she win the Democratic nomination, we can expect Harris to make a forceful counterargument to a Trump campaign that is so confident in its prospects in November that it named a running mate whom polling found is unlikely to boost Trump’s electoral prospects.

Such forceful counterarguments were already on display in her media and campaign appearances in the aftermath of Biden’s lacklustre debate performance, in which she passionately defended the administration’s record while also highlighting the threats she deems a second Trump administration poses.

Given that Harris’ first comments to the nation after being endorsed by Biden saw her pledging to “unite the Democratic Party – and unite our nation – to defeat Donald Trump and his extreme Project 2025 agenda”, we can expect the 2024 race will continue to be one defined by negative partisanship. With the vice president doing only marginally better than Biden in head-to-head matchups against Trump, Harris has a lot to do in a exceptionally short amount of time.

As a senator prosecuting political opponents, a presidential aspirant questioning Biden’s fitness for office, and a vice president rallying voters on abortion rights, Harris has clearly performed well in the past. At this point, she will have to do far more and far better than ever.

Jared Mondschein is Director of Research, US Studies Centre, University of Sydney.

This article was first published on The Conversation.