CNN  — 

Kamala Harris on Tuesday night faces a task unprecedented in modern political history. On the debate stage in Philadelphia, she will deliver both an opening argument – to the millions of voters who want to know more about her – and a closing argument – for her candidacy and against Donald Trump’s – as their lightning campaign enters its final eight weeks.

The former president will also find himself in uncharted waters. After skipping the Republican primary debates, Trump will now square off with his second Democratic rival in as many outings – but unlike President Joe Biden, whose campaign imploded onstage in Atlanta in June, Harris presents a vastly different challenge.

Harris has so far enjoyed a charmed campaign. She pounced on the nomination after Biden dropped out in July, then surged – in the polls and on the fundraising front – in the following weeks. Her cash advantage is clear. She raised $361 million in August alone, nearly three times Trump’s haul. But the horse race is as close as ever, and there is increasing demand in the electorate for more information about Harris and her policy agenda – a knowledge gap that creates opportunities and stumbling blocks for both camps.

There is less mystery surrounding Trump. This is his record seventh presidential general election debate. On the trail, he has thrown out a typically Trumpian mish-mosh of often self-contradicting pledges and positions, promoted then fled from the now-infamous “Project 2025,” and otherwise sought to tie Harris to Biden’s record, particularly on the border, while frequently issuing gender- and race-baiting personal attacks.

The fundamental question ahead of their meeting in Philadelphia, one of the highest-stakes national debates in a generation, is whether – and how – one of them can deliver a compelling message to swing voters while bolstering the confidence of their respective bases.

Here are six things to watch for on Tuesday night:

Will Harris deliver the policy message voters say they want to hear?

Harris has been vice president for nearly four years and spent about the same amount of time before that on Capitol Hill, as California’s junior senator. She ran for the 2020 Democratic presidential nomination. Still, 28% of likely voters in a recent New York Times/Siena College poll said they needed to know more about her.

For Trump, the figure was 9%.

More than her convention speech, the debate will provide a platform for Harris to answer some of those questions. So far, she has drilled down with particular focus on two issues: cost of living and reproductive rights. The latter is an obvious place of strength. Her position is vastly more popular than Trump’s and her ability to speak about it is significantly stronger than Biden’s. It also fits neatly into a broader message about personal freedoms.

The economy is a stickier wicket. Her campaign has, so far, sought to stay close to what the Biden administration has been preaching while, at the same time, injecting it with a populist freshness that excites Democrats and wins over skeptical undecided voters.

And while there’s little reason to expect Harris to deviate from her strategy, which has been to speak in broad terms while rationing specifics, she will be pushed – by the debate moderators and, in his own way, Trump – to provide a clearer picture of how she ranks her priorities.

Harris is also likely to be pressed on some recent policy switcharoos. Plastic straws are back in, for example, after she once suggested banning them, while “Medicare for All,” in all its forms, is out.

The second Harris presidential campaign has offered a significant correction of the first, an uneven primary bid that flamed out before a vote was cast. So many of the things Harris expressed openness to, if not outright support for, are now off the menu five years later. Where she is now seems both closer politically to Biden and her own long political history.

Allies describe it as an evolution, evidence of her open and inquisitive mind.

Rivals, led by Trump, tell it differently. To them, Harris’s shifting positions represent a lack of political scruples and an overabundance of ambition. With Trump, goes the familiar argument, the people know where he stands, whether they agree or not.

So which narrative will win out Tuesday night? The question is as much for Trump as it is for Harris. The vice president will surely enter with a plan to funnel the expected criticism into a more front-footed message about her plans going forward. The risk there is being seen as disingenuous, in not acknowledging what’s plain to see.

Trump, though, has a habit of overplaying a good hand. Staying focused on the specifics would seem the wiser path, given his apparent inability, or refusal, to launch a personal attack not juiced up with outrageous or bigoted language.

This image shared by ABC News shows the stage in Philadelphia ahead of the debate between Harris and Trump.

Which Trump shows up onstage in Philadelphia?

Trump turned 78 about two weeks before he took the stage with Biden in Georgia. And while the president’s difficulties rightfully dominated the post-debate narrative, Trump, too, appears diminished from his first and second campaigns.

Last week, the former president was asked at economic forum if he would “commit to prioritizing legislation to make child care affordable” and, if so, what “specific piece of legislation” he planned to champion. His response was rambling and incomprehensible. (CNN’s Zach Wolf tried his best to make sense of it.)

Perhaps worse, it was not an aberration.

Trump has for many years spoken in a digressive, unwieldy vernacular. But the digressions have become more frequent and the unwieldiness increasingly difficult to square. Given the manner of Biden’s election exit, it seems likely that the former president’s own words will come under greater scrutiny this time out.

The other half of the equation deals with what Trump says when he is, at least in form, speaking clearly.

He has already accused Harris, a Howard University graduate and the daughter of Jamaican and Indian immigrants, of deciding to “turn Black” for political reasons. Trump’s allies are fond of dismissing Harris as a “diversity” hire.

Though similar lines might rile up his MAGA base, they play poorly in the suburbs – home to the vast majority of undecided voters – and stiffen the backs (and further open the wallets) of Democrats.

For her part, Harris has strained to avoid talk about the “historical nature” of her run, figuring that is self-evident, and in her recent interview with CNN’s Dana Bash, she bypassed a chance to respond to Trump’s bizarre charge.

“Same old, tired playbook,” Harris said. “Next question, please.”

Welcome to closed mic night!

There is a strong case to be made that Trump lost the 2020 election to Biden on the night of their first debate.

Belligerent, boisterous and, the country learned shortly thereafter, battling a Covid-19 infection, Trump offered an unflattering parody of himself. Their contest was, of course, close in the end. But no one would deny – well, almost no one – that Trump hurt his chances that night.

History in mind, his campaign and Biden’s agreed before their June debate to mute the candidates’ respective microphones when the other was speaking. Trump literally could not interrupt Biden. As it turned out, he had no reason to – the president interrupted himself over and over, often trailing off at the end of his allotted time. Trump, with a few exceptions, did the politically wise thing and let Biden’s words hang in the air.

Though she stumbled occasionally on crowded stages during the Democratic presidential primary in 2019, Harris is generally regarded as a sharper debater than even a full-strength Biden. Her campaign’s push to reopen the microphones, ultimately abandoned shortly before the debate date was set, underscored its desire to give Trump the freedom to implode.

The interplay between Harris and Trump will be more strictly regulated Tuesday night. How apparent that will be to viewers is something to keep an eye on.

Remember Joe Biden?

By the end of Tuesday night’s debate, the better question might be: Are we sure Biden isn’t still running?

A little more than eight weeks since the president left the race, and with precisely eight weeks until the election, Trump’s most consistent argument has been that Harris, for all her talk of turning the page, offers more of the same.

President Joe Biden speaks at the Democratic National Convention in Chicago on August 19, 2024.

When Harris sticks by Biden’s policies, Trump attacks them and her as a failure. How she tries to parry his expected jabs on immigration and the US-Mexico border will be instructive. When Harris seeks to separate herself from her boss, in manner or practice, Trump asks why she didn’t do more over the past four years.

For Trump, it’s a simple recipe. Harris has a more complex and – if she manages it successfully – nuanced assignment.

What’s not up for debate is that Biden, though absent in person, figures to be a prominent figure on the debate stage. Harris and Trump will use, or try to obscure, his record in service of their own cases – a balancing act that, should one veer too far from the center of political gravity, risks a tumble.

Trump to face cross-examination of his abortion record – and plans

Trump has at times boasted of appointing three of the six Supreme Court Justices who voted in 2022 to gut Roe v. Wade, ending federal protections for abortion. “I’m proud to have done it,” he once proclaimed.

Since then, most Republican-controlled states have imposed either bans or restrictive new laws on the procedure. Some of those efforts were beaten back or overturned by ballot measures organized by abortion rights activists – results that, along with lopsided polling, underscore the unpopularity of the decision and its consequences.

Trump was already out of the White House when the high court’s decision came down. Though he did not personally feel the backlash, his party did, most notably underperforming expectations in the 2022 midterms as Democrats railed against the ruling and some Republicans’ determination to implement a broader federal ban.

The former president himself has offered a variety of positions and takes on the issue, the most consistent being that abortion policy should be determined by the states. Asked what state policies he supports, Trump has failed to deliver a clear answer.

Most recently, he announced he would vote against protecting abortion rights in his adopted home state of Florida, where a ballot measure would wipe out the state’s six-week ban, which Trump also says he opposes.

Harris, the former prosecutor, will try to make her rival stake out a clear position.

How does Harris address the war in Gaza?

Russian forces have been in Ukraine for more than two-and-a-half years. The fighting has been brutal, recalling the eastern front during World War II. Hamas’ deadly October 7, 2023, raid inside Israel set off a now 11-month-old bombardment of Palestinians in Gaza by the Israeli military.

Neither conflict appears near a close as the death tolls grow and the humanitarian situation in Gaza worsens.

To hear it from Trump, Russian President Vladimir Putin – with whom he claims to have a special friendship – would have never invaded Ukraine if the former president was still in charge, while Israel would be given even freer reign in Gaza than it has enjoyed with Biden in the White House.

Because of the diverse, fragile Democratic coalition that she needs to keep onside, Harris, who unreservedly supports continued Western aid to Ukraine, has been less clear on her Middle East plan.

Both in her convention speech and on the newly minted “issues” page on her campaign website, Harris has made the case for Israel’s defense, along with the creation of a neighboring Palestinian state, and security for both. Critics say she is cutting the proverbial baby in half.

For the first time, though, she will deliver that rhetoric with Trump lying in wait.