The American presidency invests a tremendous amount of decision-making power in the hands of a single person. Presidential power steadily accumulated throughout the 20th century, and has recently been supercharged by a disastrous Supreme Court ruling that has created, out of whole cloth, wide-ranging immunity from prosecution for sitting and former presidents. Now the crisis gripping the Democratic Party has revealed yet another way in which, in the US system, one person can hold all the cards.
US President Joe Biden and most Democrats were quietly confident that as Americans re-engaged with former president Donald Trump, they would remember what they deeply disliked about him. When Mr Trump was convicted on all 34 felony charges in the adult film actress hush money case, Democrats became even more convinced that they had excellent chances for the White House, the House, and even the Senate.
However, after Mr Biden's disastrous debate performance, their election plan appears shattered. While few elected Democrats have openly called for Mr Biden to step aside, panic in the party is widespread.
The liberal press is virtually unanimous that Mr Biden should make way for someone younger. Some even frame the conundrum as when and how, but not if, he will go.
The main worry is that his evident aging-related decline – which was already concerning voters before the debate – had now effectively balanced out Mr Trump's character as the key distinction. Swing voters will no longer be choosing between a convicted felon, adjudicated sexual abuser and serial fraudster, versus a president who has disappointed many Americans with inflation, high interest rates and similar perceived "kitchen table" policy failures. Instead, it will be between that same convicted felon and a president many Americans now fear may not be robust enough to campaign or govern effectively.
Alarmed Democrats doubt they can make the election a referendum on the conduct and character of Mr Trump, as they intended, when it may be also and even as much a referendum on Mr Biden's perceived ability to perform for the next four years.
The US President, however, is dismissively insisting that only "God Almighty" can stop him from running and winning. He unconvincingly insists that polls are simply wrong. The voters, he says, have shown they will stand with him and want him to keep running.
Mr Biden's jarring confidence comes from a career of being written off, only to bounce back. That certainly happened when he came from nowhere to win the South Carolina primary in 2020 and seize control of the Democratic nomination. He's clearly relishing the opportunity to once again defy the odds and prognosticators, and create a "comeback kid" narrative of perseverance and ultimate victory in the face of daunting adversity.
Only Mr Biden's opinion ultimately counts. In the primaries he won virtually all of the committed delegates to the upcoming Democratic convention – or an earlier vote on August 5 which has been scheduled to officially select the candidate earlier because of an election law in Ohio – and unless he releases those delegates, they are bound to him. There is nothing anyone else can do about it.
Mr Biden insists he will stay. Even if they wanted to, other Democrats cannot push him aside, no matter how alarmed they may be. So unless something dramatic happens, Mr Biden will apparently stay the course.
After all, he could be right. It may well be that American voters will ultimately not care too much about his age and will focus instead on his accomplishments and commitment to US political traditions and values. But given the opponent is Mr Trump, can it be the right moment for such a dicey experiment?
This nail-biting process will play out until formal candidate selection. Frustrated Democrats compare the situation to a grandfather refusing to give up his car keys after persistent erratic driving and a terrible crash.
The most appealing alternative – Mr Biden stepping aside, releasing his delegates without endorsing anyone, and initiating a quick process to select a different candidate – is barely plausible. Every day he hangs on, it becomes more remote. Only one other Democrat has the national machinery in place, more than $280 million in campaign funds, and the enormous advantage of incumbency.
The only practical alternative is Vice President Kamala Harris. Her name is already scheduled to be on ballots being prepared around the country. She is in the White House now and can run as a surrogate incumbent. She can seamlessly inherit the campaign staff and funds she already shares with Mr Biden. And her candidacy would not split the party coalition the way a divisive free-for-all between other leading Democrats might. She could even energise many despondent Democratic voters.
If Mr Biden is ultimately persuaded to step aside in time, Ms Harris will be his replacement. Some Democrats have long dreaded this, but there's no reason she couldn't effectively pursue a campaign all about Mr Trump, including his own evident age-related decline.
Mr Biden's recent television appearances and other efforts to demonstrate his continued viability have done little to reassure his panicking supporters. They fear he could have another public meltdown, possibly on several, or even many, occasions before the election.
It will be hard for him to quickly regain the confidence of his own party elite. Many who love him are haunted by the prospect of a tragic denouement to his career, with his egotism and ambition avoidably returning a presumably supercharged, vengeful and authoritarian Mr Trump to the White House, armed with new and unheard-of impunity courtesy of the US Supreme Court.
On Thursday, Mr Biden will face his biggest, and potentially decisive, test since the debate debacle at a 45-minute unscripted press conference at the Nato summit in Washington. If he demonstrates command, assurance and solidity, efforts to convince him to step aside will probably be abandoned for the time being.
But if he does poorly, the President may find himself increasingly pressed to rapidly hand control of the campaign, and even the presidency, to Ms Harris. Mr Biden insists he can still do the job, which includes campaigning against Mr Trump. He's going to have to prove that in short order to regain the confidence of his own party leaders. As so often in US politics, it all comes down to one person.
