Five nights ago, I stood on the tarmac at Dover Air Force Base and watched Joe Biden, wearing a dark jacket and baseball cap, gingerly descend the staircase of Air Force One.
From my position in the travelling press pool, I saw each unsteady step downward being scrutinised as closely as his acts of office. From the plane emerged an inescapable scene of frailty. The human weakness of age seemed to have overcome the most powerful man on earth.
Mr Biden, 81, had just tested positive for Covid. We had flown back with him from Las Vegas in what became a debilitating end to a trip meant to see him hitting the campaign trail with full force.
The scene at Dover, now being replayed over and over on the news channels covering his election exit, was his last public appearance before he pulled out of the race on Sunday. If feels now like the image of the end of his candidacy.
So much changed in a week.
Last Monday, when I and other press joined him aboard the presidential plane for that campaign trip to Nevada, the president clearly felt the Democratic nomination was still his to hold onto.
Donald Trump had dodged an assassin’s bullet two days earlier, giving Mr Biden a political reprieve from the growing calls from Congressional Democrats for him to step down from the race.
His campaign hoped the trip would reinvigorate black and Hispanic voters who traditionally overwhelmingly back the Democrats but whose support for Mr Biden had slipped since 2020.
On Tuesday, I watched him energise a packed convention hall with a speech to the African-American civil rights group the NAACP. I spoke to some delegates who were literally dancing in the aisles before Mr Biden’s speech. “Four more years” echoed through the venue.
But the next morning, things began to spin out of control.
The end of the road was the Original Lindo Michoácan Restaurant, Las Vegas, Nevada. This was one of those highly orchestrated campaign stops where the president mingles with voters. The press was ushered inside to capture the president’s entrance. As the door swung open, I was struck by how pale he looked, and how much slower he seemed than the day before as he shook hands with diners.
We shouted questions about the growing list of Democrats questioning his fitness to run – he didn’t answer. Then we were hustled back out to the press vans while he did a radio interview inside.
We waited. And waited. In the searing Nevada heat we spent more than 90 minutes in the press vans with the entire motorcade stalled. It was by now obvious that something was wrong. Suddenly, an email dropped from a BBC colleague to say the host of his next speech venue had announced, on stage, that Mr Biden had just tested positive for Covid.
As I tried to approach a White House staffer to find out what was going on, I was abruptly ordered to get back in my van, and told that we were leaving. The motorcade began rolling and we were speeding our way through the suburbs of Las Vegas, destination unknown. The campaign was changing course. Suddenly, amid the flashing lights and police outriders, the airport came into view. The president was going home to Delaware to recover from Covid, the campaign trip was over.
Soon his campaign would be too, when he made the announcement that he was no longer running for president from his beachside home just days later.
In hindsight, his last appearance at the air force base in Dover seemed like a final attempt to defy the inevitable, what campaign-donor George Clooney called “the battle against time”.
On the tarmac we had asked him, one last time, about waning Democratic support. This time, he answered back: “I’m doing well”. It wasn’t quite what we had asked, not really. Maybe he misheard us, or maybe he meant he believed he could survive it.
It turns out he couldn’t.