Here's what could actually move the 2024 needle during tonight's debate

Joe Biden and Donald Trump will have just 90 minutes tonight to set the tone for the next phase of the presidential campaign — and, perhaps, shake up a stagnant race.

The blockbuster showdown , which takes place months earlier than normal and outside of the traditional bounds of the Commission on Presidential Debates, will mark the first time the two men have been in the same room together since 2020.

POLITICO reached out to some of the smartest strategists and power players in politics to ask them about the biggest single thing they’re watching for tonight — and what they’re most worried about for their party’s standard-bearer.

Here are there responses, edited for length and clarity:

Neil Oxman, Pennsylvania-based Democratic strategist: If Trump acted like a normal human being for 90 minutes and wasn’t crazy — and he disagreed with Biden and was respectful and just talked normally — he’d pull a lot of independents toward him very quickly. Biden has to be as bright and energetic as he was at the State of the Union . He just can’t be bumbling. Substance matters if you make a mistake — and there have been mistakes in debates that have come back to haunt people.

The way this campaign is now, Biden might be a point or two behind, within the margin of error, in most of the swing states. And he has an opportunity here — one of maybe only two where you really have a chance to change the dynamic and have people look at you.

I’m worried that Biden isn’t going to be an "A," and I think he has to be an "A."

Douglas Heye, veteran GOP strategist and former communications director for the Republican National Committee: Can either of these candidates do anything to improve their high disapproval numbers and sway those double-haters? For Biden, that’s demonstrating that he understands voter concerns about both consumer prices and the border. That’s true for Trump, as well, but also that he can stay focused on issues. If Trump does throw sand in Biden’s eyes, how does Biden react?

Lastly, which — if either — candidate demonstrates to voters they have the stamina to be president for another four years. This is especially risky for Biden. If he has a bad night, it could be curtains. If he has a good night, Democrats will call it a game changer. But that’s what they said after SOTU, and the game did not change.

Maria Cardona, Democratic strategist: The biggest thing I am watching for is which version of Donald Trump shows up. Crazy, unhinged, off-the-rails Trump or a more calm, disciplined, focused Trump, and how Biden will respond to each version. Regardless of whether Trump Jekyll or Trump Hyde shows up, President Biden needs to be ready to go on offense on all the issues on voters’ minds, and be ready to offer the stark contrast [between him and Trump].

Mary Kate Cary, former speechwriter for President George H.W. Bush: Can both Biden and Trump make a positive case for what they’ll do in the next four years? The candidate who is better at taking the high ground — laying out effective policies and an optimistic agenda for a stronger America — will be the one to gain enough votes in swing states to win. They should talk to those voters, not at each other. I’m curious to see if either candidate realizes what an opportunity that is, since the first debate usually reaches the most voters.

I’m concerned about how the new “muted mic” rule will play out. Will Trump use it to his advantage and avoid the interruptions, insults, and anger of their first debate back in 2020? He’d do well to stay calm and let Biden speak. That alone could win the debate for him. Or will the moderators use the new mic rule to take sides and silence one candidate over the other (and we can guess which candidate that would be)? Another option: The two will be muted on the television feed but not in the studio, since they’ll be within hearing distance of each other. They could still try to provoke each other without the rest of us hearing them — remember Al Gore’s sighing and eye-rolling in that first debate against George Bush in 2000? As the New York Times put it, Gore was “undone by impulses he could not control.”

Pramila Jayapal, Democratic representative from Washington and chair of the Congressional Progressive Caucus: Obviously [in 2020, Biden] wasn't able to get a word in edgewise because he kept being interrupted [by Trump]. So I think that they've created the conditions where we should be able to really see what each person is about, and what they stand for and what they've delivered.

Chris Sununu, the Republican New Hampshire governor who is supporting Trump after backing former South Carolina Gov. Nikki Haley in the Republican primary: Watching each candidate’s body language will be very interesting. It will tell you a lot about their emotional confidence regardless of what their answer to the question is.

[My concern is] that [Trump] caters to the extreme elements of the party instead of tailoring his message to all Republicans and independents.

Joseph Geevarghese, executive director of the progressive group Our Revolution: There’s a real economic squeeze on everyday Americans, and the president’s got to acknowledge that pain, and he’s also got to articulate what he is going to do in the next four years to address that concretely.

There’s a battle here between two senior citizens. And I do think the Republicans, Trump, have very effectively articulated a case — whether accurate or not — that Biden is not fit for office because of his age. And Biden’s got to come out swinging. He’s got to do a repeat performance of the State of the Union and show that he’s quick on his feet, that he can take on a bully like Trump and not stumble and not verbally make any gaffes.

Whit Ayres, Republican pollster and president of North Star Opinion Research: I’m watching how the two candidates come across far more than what specific positions they take on issues: whether or not Biden seems like the Biden of the State of the Union or the Biden who too often seems like a senile old man. And whether Trump can come across, as he did on the recent David Sacks podcast, as a coherent and rational and reasonable person, or if he’s the Trump of the first debate against Biden in 2020.

Only about 15 percent of Americans are OK with these two candidates. According to Pew data, 85 percent would replace one or both of them on the ticket if they could. That is not healthy for democracy, when the Democratic system offers up two choices who are so distasteful to the majority of Americans. So I’m hoping that one or both of them seems like someone that Americans can be comfortable with over the next four years.

Philippe Reines, longtime Hillary Clinton adviser who played Trump in her 2016 debate preparations: I’ll be watching the introduction and their walking on stage. These two haven’t seen each other in 1,343 days. They’re not fond of each other. Plus, Trump will be triggered in ways he might not even realize. When’s the last time he wasn’t the biggest big shot in the room? He’ll be introduced as a “former” — which probably doesn’t happen at Mar-a-Lago weddings or UFC MMA events. His plane will have had to idle in deference to Air Force One. His motorcade is smaller. The animosity will be seismic and immediate. As Mike Tyson said, everyone has a plan until they’re punched in the face. Don’t discount the impact of such emotionality on a candidate’s performance. It would manifest itself differently in each. Such a dynamic would redound to President Biden’s favor. Not so much for the former.

One concern is in an area I can’t believe I’m saying with a straight face: Policy. Unless Trump is muted for all 90 minutes, the lies will fly. So it might seem to viewers like a blow landed when in fact he threw a punch below the belt that Biden and the moderators couldn’t process fast enough to call bullshit. This is the type of attack Trump relishes and relied on during the 2015 Republican primary season.

Charlie Gerow, Pennsylvania-based Republican strategist: I’m going to watch to see how badly Biden falters. That’s probably the No. 1 thing. How often he demonstrates he’s not fully in command of the facts or the situation.

The standard concern is probably that [Trump] would veer off the road of propriety — that he goes places he doesn’t need to go. He doesn’t need to beat up on Biden to be successful. Biden will beat himself up. The facts are with Trump. He doesn’t need to gild the lily.

Celinda Lake, president of Lake Research Partners and a Democratic pollster who works with the Biden campaign: I’m not worried about Biden. He’s an excellent debater and just has to follow his State of the Union presentation.

Fergus Cullen, former New Hampshire GOP chair and “Never Trumper”: Biden needs to demonstrate that he has the ability to carry this fight over the next five months. He’s got to be strong, he’s got to be in command and in control. He needs to be able to show he can stand up to Trump’s hectoring and bullying. And I do think the format — turning off the mics, no studio audience — those things help set an environment where he’s got a better opportunity to do that.

What I’m worried about is a so-so, underwhelming performance from Biden. He can’t get a gentleman’s "C." He either needs to have a very strong performance or it needs to be disaster so bad that desperate times call for desperate measures and [Democrats say they] can’t go into this fight with this person as their boxer and they need to make a big change in their entire ticket, because Kamala [Harris] is not the answer either. A middling performance that has the Democratic Party wringing its hands but not actually galvanized to take action is the worst. He either needs to win or he needs to lose badly.

Antjuan Seawright, South Carolina-based Democratic operative: First and foremost, if the former president will show up. There’s still no guarantee that he will show up. But we’ll see. More than anything, the defense or articulation of their record and their vision for the next four years. They both have this commonality, they both served in the office for at least four years, and so there's great discussion about who's done what for whatever constituency.

I hope the president does not get drawn into the bullshit arena with the former president. He's going to say things that are just simply not true. While Biden should certainly call out his lies and push back on his lies, I don't think he needs to get into this necessary tiff to the point where it makes even more people perhaps tune out or become even more politically frustrated. So the president has to walk a very fine line of defending and protecting his record and his administration and his presidency, but not get drawn into a fight.

Barrett Marson, Arizona-based Republican strategist: How Trump walks that fine line [on abortion] in his very Trumpian way is going to be the biggest question not just in this debate but in the months going forward. He will be pushed beyond his talking point. I don’t know if he’ll be able to just hem and haw his way out of it. And voters will want an honest answer on that issue.

If Trump sticks to the issues people care about — which are the economy and inflation and the border and immigration, and which the Biden administration has done a poor job on, there is no doubt — then he has a really good chance of convincing people, convincing swing voters, that he deserves another crack at the White House. But there’s no point in telling him to stay on script. That’s just not what he does.

Michelle Wu, Boston mayor: I hope that the debate will highlight what people care about most, which is not the messy personal drama but what has our government accomplished for Americans under each of these administrations. There’s a clear difference in the outcomes and what can be measured and the quality of life that we’ve seen then and now.

Matt Mowers, GOP strategist who has worked on presidential campaigns for Trump and former New Jersey Gov. Chris Christie: I’m watching for which candidate brings something most to surprise the American public by revealing something new. There’s a perception that President Biden is shaky. Does he show up with strength? There’s a perception that President Trump is all bluster. Does he show a substantive side like he has recently on the various podcasts he’s been in where he’s announced new policy? They are the two best defined candidates in history, and it will be one of the few moments to possibly expand their appeal.

Mia McCarthy contributed to this report.