The bizarre gaffe that sealed Biden’s fate… his dirty tactics exposed… and his botched response to the most important question of the night: Your essential guide to all the debate drama, by SCOTT JENNINGS

President Joe Biden’s senior advisers, aides and First Lady have a lot of explaining to do.

For weeks, they assured America that the 81-year-old presumptive Democratic Party nominee was fit and capable, and would not only serve out his term, but another four years.

Americans were told not to believe their lying eyes, that the man they saw freezing at public events and rambling incoherently when speaking off the cuff was actually as sharp as a tack behind the scenes.

Where was that man at Thursday night’s debate?

The future of Joe Biden’s campaign depended on this one test: the first showdown of the 2024 election. And he failed.

Ironically, this was the confrontation Biden’s campaign wanted.

President Joe Biden’s senior advisers, aides and First Lady have a lot of explaining to do.

In May, his team released a video — compiled from six shots — in which the president challenges Trump to a debate.

“Make my day, buddy,” Biden boasted.

Well, Mr. President, you got what you asked for.

Here are the key moments when Democrats are now in full-on panic — wondering if there’s time to swap their candidate for another before voters go to the polls in November.

MOUTH AGAPE AND CONFUSED

From the moment President Biden took the stage in Atlanta, millions of Americans watching knew something was wrong.

His appearance was, frankly, shocking: his mouth open and his eyes closed.

Then he opened his mouth – and it was worse.

His voice was weak. His thoughts wandered.

Throughout the 90-minute debate he was often difficult to hear and completely unintelligible.

From the moment President Biden took the stage in Atlanta, I and millions of people watching at home knew something was wrong.

At one point, Biden inexplicably moved from a discussion about abortion policy to crime against illegal immigrants.

“There are a lot of young women being raped by their… by their in-laws, by their… by their husbands, by their brothers and sisters, by… just… it’s just… it’s just ridiculous.” , he said.

Ridiculous, indeed.

Even the Democrats were surprised.

“There’s a sense of shock at the way he came out at the beginning of this debate about what his vote sounded like,” said David Axelrod, a former chief strategist for the Obama campaign. “He seemed a little disoriented.”

JOE IS CONSUMING

As the debate drew to a close, President Biden became agitated — with flashes of anger and insults.

Predictably, he criticized Trump as a “convicted criminal,” but then he got disturbingly more specific.

He first falsely claimed that Trump owes “billions of dollars” in fines for “publicly harassing a woman.”

Trump has appealed a defamation case he lost against writer E. Jean Carroll. She alleged that he sexually assaulted her in a department store decades ago.

As the debate came to a close, President Biden became agitated — flashing anger and insults.

Then Biden went further, spitting at Trump that he “had sex with a porn star,” adding “while your wife was pregnant.”

These accusations against Trump are well known. They won’t do much to change voters’ minds.

However, they do make Biden look pathetically desperate.

NOT DELIVERED

From the economy to the border, from foreign policy to health care, Trump delivered the most effective and impactful speeches of the night.

The former president effectively contrasted his stewardship of America’s longest war with Biden’s botched withdrawal from Afghanistan, which resulted in the deaths of 13 U.S. service members and 170 Afghans.

“I left Afghanistan, but we left with dignity, with strength, with power,” Trump said. “He left, it was the most shameful day in the history of our country.”

Trump was also the clear winner on immigration time and again.

I would like to ask [Biden] why he allowed millions of people to come here from jails, prisons and mental institutions to come into our country and destroy our country.”

He predictably labeled Trump a “convicted felon,” but then became disturbingly more specific.

Polls routinely show that voters trust Trump more than Biden on this issue, which is among their top concerns. After tonight, that poll margin will only increase.

And of course there’s the matter of the economy – and the persistent inflation that eats away at Americans’ paychecks.

‘[Biden] “We inherited virtually no inflation,” Trump noted, “and it stayed that way for 14 months. And then it exploded under his leadership, because they spent money like a bunch of people who didn’t know what they were doing.”

BIDEN CAN’T ANSWER THE MOST IMPORTANT QUESTION

CNN host Dana Bash saved the best question for last.

“President Biden, you would be 86 at the end of your second term. How do you deal with concerns about your ability to do the world’s toughest job well into your 80s?’ she asked.

The president’s answer is – in short – not good.

“I spent half my career being criticized for being the youngest person in politics… And now I’m the oldest,” he replied, before launching into a meandering list of his record, which includes inventing “computer chips” and visits to South Korea.

Before Thursday evening, most Americans already thought Biden could not serve another four years as president.

If they are honest, I’m sure they will all agree with that assessment.

Biden’s candidacy is prepared.