ATLANTA — In a presidential election rematch that remains extremely close and where every vote may count come November, it's no understatement to say that there's an incredible amount at stake in Thursday's first of two debates between President Biden and former President Trump.

The two presumptive major party nominees will face off on the same stage at the CNN Presidential Debate, which is being held at the cable news network's studios in Atlanta, the largest city and capital of the crucial southeastern battleground state of Georgia.

"This is a toss-up race and there’s over two months until the next debate. This showdown is going to set a tone and a narrative heading into this summer’s conventions," longtime Republican strategist and communications adviser Matt Gorman told Fox News, as he pointed to the earliest general election presidential debate in modern history. 

And Gorman, a veteran of numerous GOP presidential campaigns, emphasized that the debate, which will be simulcast on the Fox News Channel and on other networks, has the potential "to change the narrative in a massive way" as Biden and Trump "try to break out" from the current status quo.

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The debate, which kicks off at 9pm ET, will be 90 minutes in length, with two commercial breaks. 

Only the Democratic incumbent and his Republican predecessor will be on the stage, as the third party and independent candidates running for the White House – including Robert F. Kennedy Jr. – failed to reach the qualifying thresholds. 

To make the stage, candidates needed to reach at least 15% in four approved national surveys and to make the ballot in enough states to reach 270 electoral votes, which is the number needed to win the White House.

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Trump and Biden bypassed the Commission on Presidential Debates – which had organized these quadrennial showdowns for over three decades – and instead mutually agreed on the rules and conditions.

Those include no studio audience, each candidate's microphone will be muted except when it's their turn to answer questions, no props or notes allowed on stage, and no opening statements.

There will be closing statements and a coin flip determined that Trump will get the final word.

The debate comes as polls indicate a very tight race between Biden and Trump, with the former president holding the slight edge in many national polls and surveys in the roughly half-dozen or so battleground states that will likely determine the election's outcome.

"To put it very simply – debates move numbers in a way few other events do. Period," Gorman highlighted. "And with over two months to go until the second debate [an ABC News hosted showdown scheduled for Sept. 10], the narratives formed on Thursday night may harden into concrete, so showing up and performing well in Atlanta is crucial."

Both candidates come into the debate with an ample amount of baggage that will offer their rival plenty of potential ammunition.

The 81-year-old Biden, the oldest president in the nation's history, for months has faced serious concerns from voters over his age and physical and mental durability. He's also been dealing for nearly three years with underwater job approval ratings as he's struggled to combat persistent inflation and a crisis at the nation's southern border, as well as plenty of overseas hot spots.

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Meanwhile, Trump made history for all the wrong reasons last month, as he was convicted of 34 felony counts in the first criminal trial ever of a former or current president.

Three and a half years after the Jan. 6, 2021 attack on the U.S. Capitol by Trump supporters trying to upend congressional certification of Biden's 2020 election victory, Trump faces criminal charges of trying to overturn the results of the last presidential contest. His promises of second-term retribution against his political enemies have created a backlash, and he's struggled along with plenty of other Republicans to deal with the combustible issue of abortion two years after the Supreme Court struck down the decades-old Roe v. Wade ruling. 

Arguably the biggest question surrounding Thursday night's debate is which version of Trump will show up?

Will it be the undisciplined candidate who continuously interrupted Biden and debate moderator Chris Wallace dozens and dozens of times at their first debate in the 2020 election? 

Trump appeared to lose his cool, failed to condemn white supremacists, and his performance was widely panned by political pundits and viewers alike.

Or will it be the Trump of the second 2020 debate, when the then-president re-worked his strategy and his disciplined and measured performance was a vast improvement.

"If he replicates that performance, Donald Trump’s going to have a very good night," longtime Republican consultant and veteran debate coach Brett O'Donnell told Fox News.

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O'Donnell said his advice to Trump is "watch the second debate you had with Joe Biden in 2020 and replicate that performance. Watch it over and over and replicate that performance in this debate."

"He was measured but firm," O'Donnell said of Trump. "You can be aggressive and passionate without being offensive."

O'Donnell knows a bit about coaching presidential candidates ahead of their debates. He assisted in debate preparations for George W. Bush in 2004, GOP presidential nominee Sen. John McCain of Arizona in 2008, and Republican standard-bearer and then-former Massachusetts Gov. Mitt Romney in 2012. 

This election cycle, O'Donnell coached Florida Gov. Ron DeSantis ahead of his debate performances in the Republican presidential primaries.

O'Donnell said Biden needs to be careful not "to fall into the incumbent trap… Many if not most incumbents in their first debate, whether it’s Ronald Reagan or George H.W. Bush or George W. Bush or Barack Obama, most incumbents perform poorly in their first debate going for the second term."

"So the advice to Biden is avoid the incumbent trap because if he falls into it, it’s doubly bad because of all the age arguments," he added.

And O'Donnell emphasized that Biden has "got to somehow frame the race as a choice in defense of his record over the past four years. That is a tall order, but that’s something he has to do in order to justify picking him over Donald Trump."

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.