DEMOCRAT Kamala Harris and Republican Donald Trump will battle each other on Tuesday in their first televised debate, a high-stakes clash that could give the winner an advantage in the final sprint to Election Day.
For Harris, the square-off in Philadelphia is an opportunity to lay out her priorities and show her mettle against a rival who has belittled her intelligence and subjected her to racist and sexist attacks.
Trump will get a chance to try and blunt some of Harris' momentum in a race that has tightened considerably since she became the Democratic nominee in July.
Most opinion polls show Harris to be slightly ahead nationally and in the majority of battleground states, but Trump remains well within striking distance to win the Nov. 5 election.
Debates can be enormously consequential, and this could be their only one. President Joe Biden dropped out of the race after a faltering performance in June.
In 2016, however, Hillary Clinton was considered to be the victor in all three of her debates against Trump, but he won the election.
Here's what to watch for in the pivotal televised event:
CHANGE CANDIDATES -- In an election that features a former president facing the current vice president, both candidates are somewhat paradoxically portraying themselves as "change" candidates who will upset the status quo.
Harris is seeking to take credit for the achievements of the Biden administration without being weighed down by its missteps, while also suggesting her presidency would mark a fresh start for the country.
Despite four years in the White House from 2017-2021, Trump has again styled himself as an insurgent pushing back against the institutions of Washington.
But he also has played up his experience on the world stage as compared to Harris, pledging for instance that he could bring to an end the conflicts in Ukraine and Gaza and protect the country from a nuclear-armed North Korea or Iran.
GETTING PERSONAL -- Since Harris became the nominee, Trump has questioned the authenticity of her heritage and unleashed a stream of personal attacks in speeches and social media posts, defying aides and allies who have told him to focus more on her policies.
If he repeats those attacks on the debate stage, he could alienate undecided voters, particularly those who are skeptical that he has a presidential temperament.
In his 2016 debates against Clinton, Trump frequently raged at her, interrupted the moderators, pointed fingers and called her names.
He tried the same tactic with Biden in 2020, leading Biden to say "Will you shut up, man?" after Trump had interrupted him several times.
Harris has largely ignored Trump's personal attacks so far. Some viewers will be watching for how she handles Trump if he brings his bullying approach to the debate stage.
To show the sharpest contrast with Trump, she will have to show she won't be pulled into the pit with him.
OPPORTUNITIES -- The debate is Harris' chance to establish her own political identity for millions of Americans who tune in to watch.
Harris is not as well known as the Democratic presidential candidates who most recently preceded her, which could be a huge asset in an election where voters repeatedly said they were weary of a Biden-Trump rematch.
Harris, a former California attorney general, will have a platform to show her prosecutorial skills.
She could try and hold Trump accountable for his conduct after the 2020 election, including allegations that he incited a mob of followers to attack the US Capitol on Jan. 6, 2021, in a last-ditch bid to remain in power.
Her courtroom experience may also enable her to rebut Trump's falsehoods in real time in a more effective way than Biden was able to during their June debate.
For Trump, the debate affords him his best chance yet to assert that Harris isn't ready to run the country and that he's the better choice for the job.
Trump likely will attack Harris over the Biden administration's border-security policies, which failed to stop a record number of migrants from crossing into the US before being tightened earlier this year, as well as high consumer prices that Trump argues has made it harder for middle-class families to make ends meet.
He could continue to try to pin her to the chaotic US exit from Afghanistan in 2021, raising questions about whether a candidate whose campaign has relied on "joy" and "vibes" is prepared to become commander-in-chief.
VULNERABILITIES -- Democrats have been saying for months that Trump has authoritarian tendencies and is a danger to democracy. Harris could repeat that line of attack as well as pressing him on his opposition to abortion, one of his most vulnerable political issues.
She will likely highlight his role in placing justices on the US Supreme Court who helped to do away with constitutional protection for the procedure and warn that women's reproductive rights would be further curtailed under a second Trump presidency.
Harris' aides and advisers said she plans to focus on what her team calls Trump's failures on the US border wall, infrastructure and the Covid-19 pandemic.
Harris also may slam Trump for his economic policies during his administration, arguing he showered corporations with tax cuts and opposed raising the minimum wage.
She could try to link him to Project 2025, a governing blueprint laid out by the conservative Heritage Foundation that critics say would abuse executive power. Trump has tried to distance himself from the plans.
And she might bring up Trump's felony conviction in his porn-star hush money case earlier this year as well as the allegations of sexual assault he has faced.
Trump, meantime, might remind viewers of the liberal policies Harris embraced during the 2020 presidential campaign and has now disowned, including doing away with private health insurance and supporting the so-called "Green New Deal" – a massive clean-energy programme.
Harris will need strong answers on those fronts if she is to win over independent and undecided voters. She has been content to sketch much of her vision for the presidency in broad strokes.
Trump - and the moderators - may force her to be more granular.
Progressives also will be looking to see if Harris differs from Biden on key issues such as the conflict in Gaza and if she would be willing to put greater pressure on the Israeli government to reach a ceasefire agreement.
* The writer is from Reuters