Rarely, if ever, has one candidate in a presidential debate had so much material to use against the other.

Republican Donald Trump has been convicted of 34 felony counts with serious charges in three other indictments still pending. There's also Trump's links to the January 6 Capitol riot. And his sweeping second-term plans include promises of retribution against political enemies in both parties.

Yet the big question for President Joe Biden is whether he has the physical and mental capacity at 81 years old to press the case against Trump. Perhaps nothing matters more than the level of energy and strength the Democratic incumbent projects on stage.

Both men have glaring flaws that present their opponent with tremendous opportunity – and risk. They will face a huge national audience that will include many people tuning into the 2020 rematch for the first time and who won’t see another debate until September, magnifying each success or mistake.

Biden and Trump will face off Thursday night for 90 minutes inside a CNN studio in Atlanta.

Here are some key questions ahead of the debate...

Can Biden perform?

Biden’s seeming low bar for success has been created, at least in part, by the 78-year-old Trump and his Republican allies, who have relentlessly mocked the Democratic president for apparent stumbles connected to his age for years. Trump’s allies have questioned whether Biden can even stay awake and stand up for the entire 90 minutes.

Democrats are hopeful that Biden can bring the same energy he did in his State of the Union address earlier in the year. But a face-off on live television against an opponent who delights in verbal combat is very different from a scripted speech before Congress.

Biden’s team is aware that he cannot afford to have a bad night with the nation watching.

Can Trump be boring?

Having already locked up his base, Trump has an opportunity with persuadable swing voters and moderates who fuelled Biden’s victory four years ago and now express concerns about both candidates.

But to win over the so-called “double haters”, Trump cannot simply lean into the red-meat talking points, personal insults and conspiracy theories that typically dominate his public appearances. He’ll need to offer an optimistic vision for the future and a clear contrast with Biden on traditional kitchen-table issues like health care and education.

In short, Trump needs to be somewhat boring on Thursday night. Can he stay disciplined? Some allies are hopeful. History may suggest otherwise.

Navigating the criminal records

Trump’s extraordinary legal baggage creates opportunity and risk for both candidates on stage.

Biden’s campaign has signalled an increasing willingness to lean into Trump’s criminal record in recent days. But aside from a few jabs, Biden himself has largely distanced himself from Trump’s prosecutions to avoid the appearance of political interference.

Trump, who has been alleging for years without evidence that Biden is responsible for prosecuting him, won’t make it easy for the president to toe that line.

Recent polling shows that about half of US adults approve of Trump’s New York conviction. And if voters don’t think the specific convictions are troublesome, Trump’s attempt to conceal unfavourable stories is hardly bumper sticker material.

Meanwhile, Biden is aware that Trump may go after his son, Hunter, as the then-president did on the debate stage four years ago. Hunter Biden was recently convicted on three felony charges related to the purchase of a gun. Trump has also raised questions about Hunter Biden’s foreign business dealings when his father was vice president.

Muted mics and moderators

As is often the case, the moderators and the ground rules will likely shape the debate’s outcome. And the ground rules for this debate, the first of two scheduled meetings, are unusual.

It’s worth noting that the candidates are bypassing the traditional structure determined by the Commission on Presidential Debates and instead relying on a set of mutually agreed rules and conditions.

Biden and Trump will debate at a CNN studio in Atlanta with no audience. There will be no opening statements. Each candidate’s microphone will be muted, except when it’s his turn to speak. No props or pre-written notes will be allowed on stage. The candidates will be given only a pen, a pad of paper and a bottle of water.

A coin flip determined that Trump would deliver the final closing statement.

The event will be moderated by CNN’s Dana Bash and Jake Tapper, two well-respected anchors who have tended to called out both sides on issues of the day.

Health and immigration

While style sometimes matters more than substance on the debate stage, both candidates have serious policy challenges to navigate.

For Trump, no issue looms larger than women's health. His Supreme Court appointments while president enabled the court to rule on issues which led to an avalanche of health restrictions across the nation. Trump has repeatedly said he was proud of his role in the court's decision. And Biden will be eager to highlight Trump’s role.

Biden’s greatest political liability, meanwhile, may be immigration. The Democrat’s administration has struggled to limit the number of immigrants entering the country at the US-Mexico border. His allies privately acknowledge the issue is a major political liability heading into the fall.

Trump loves nothing more than highlighting illegal immigration, so expect him to pound Biden on the issue.

At the same time, Biden will face tough questions about his leadership in the war between Israel and Hamas. The president has alienated some would-be supporters on both sides given his staunch support – and occasional criticism – of Israel.

He’ll have a major opportunity to defend his record on the complicated issue Thursday night.