The cracks beneath US President Joe Biden’s feet continue to widen.

While the shock of the assassination attempt on former President Donald Trump seemed like it might relieve some of the pressure on Biden, the story of his viability as both president and candidate continues to feed on itself.

Ever since his disastrous debate performance against Trump on June 27, the 81-year-old incumbent has been dogged by relentless questions about whether he should be running for a second term as the Democratic nominee.

And this week, the pressure has continued to mount. Senate Majority Leader Chuck Schumer, one of the most senior members of the party, “forcefully made the case” for Biden to step aside in a one-on-one conversation, according to reports. (Schumer’s spokesperson has called the reporting “idle speculation”.) Another top Democrat, Adam Schiff, has publicly called for him to exit the race, as well.

As if things couldn’t get any worse, the White House announced today that the president has COVID.

It is all getting very hard to watch.

Biden and his team need to realise there is no way for him to allay these concerns over his decline simply because he cannot get younger. He cannot prove he is not too old because he is too old.

As such, there is no good way for Biden and his campaign to approach the problem – it is, largely, unsolvable. And it is hard not to argue the efforts of the president and his surrogates to persuade the public he is still a viable candidate have only made things worse.

A growing sense of betrayal

Biden and his team have blamed his debate performance on a cold and the effects of jet lag from an overseas trip 12 days earlier. But if a president is hit so hard by a mere cold and jet lag, of course questions will be asked about his capacity to continue to lead, not just now but over the next four years.

Being the president of the United States is arguably the hardest job in the world. The person who does it, fairly or not, needs to be able to push through when they are tired and sick.

Perhaps all of this would have been eventually surmountable, though, if Biden’s political appeal – as opposed to his personal one – had any traction.

Over the last several weeks, however, Biden’s message appears to have degenerated into simply pointing out that he is not Trump. The entire point of his candidacy now appears to be a negative one – to beat Trump.

Yes, beating Trump is critical to Democrats. But Biden appears to have lost the ability to persuade Americans he can stop the deepening divisions that still plague the US and cause many to fear it is splitting apart. It is not clear what Biden’s vision for the future is or what he is offering other than another temporary stay in a much longer historical catastrophe.

This was evident at Biden’s “big boy” press conference at the end of the NATO Summit in Washington. Biden spoke at length and in great detail about foreign policy, an area he and his supporters have long considered one of his greatest strengths. But his vision for the United States’ role in the world was muddled and included some misleading comments and gaffes.

His comments on Israel, too, highlighted a much deeper problem on the electoral horizon. A day after the press conference, The New York Times published a video montage of voters explaining they cannot vote for Biden because of his administration’s support of Israel’s war in Gaza.

To these voters and others, it is hard to underestimate the depth of Biden’s betrayal, both political and personal.

In 2020, Biden’s successful pitch to the American people centred on his own compassion, his ability to see the suffering of other people, really feel and share it, and then to work to ameliorate it. He promised to both listen and to be a generational bridge. He has done neither.

His support among Democratic voters continues to decline. In a new survey this week, in fact, two-thirds of Democrats now believe he should withdraw from the race.

A party historically wary of division

Succession planning should be a critical part of any president’s job. And yet Biden – the oldest sitting president in American history – has no obvious successor, not even his own vice president, Kamala Harris. And no one else in the Democratic Party has any authority to lead until and unless he steps aside.

Everything now becomes a matter of risk calculations for a party not good at making them.

For decades, Democrats have been scarred by the inherited “lessons” of the 1968 contested convention. This was a tumultuous meeting of party members to choose a nominee for that year’s presidential election, which revealed deep divisions over the Vietnam War. The Democratic nominee, Hubert Humphrey, went on to lose the election to Richard Nixon.

Since then, Democrats have been very wary of public conflict. So it is entirely possible Biden will remain the candidate in this year’s election, that Democrats will kick the figurative can down the road until November.

However, given the stakes, they may also decide – either individually or collectively – that the risk Biden poses for “down-ballot” races (those Democrats running for the House and Senate) might outweigh the risk of ditching him so late in the campaign.

For some, this will be a question of personal risk to political careers; for others, it is a question of small-“d” democratic survival. Ensuring the Democrats do not lose both houses of Congress is widely regarded as critical to stymieing Trump’s anti-democratic agenda, should he beat Biden.

If more high-profile Democrats continue to put pressure on Biden, which appears likely, he may eventually be persuaded to step aside of his own accord, for Harris or someone else. Biden is, if nothing else, loyal to his party. This would leave time to choose another candidate and revamp the campaign.

But American politics is often wildly unpredictable. It is entirely possible there is a circuit breaker on the horizon. A candidate no one expected may emerge to unite the party, Harris may step up, or some outside event may change everything in an instant (such as the attempted assassination on Trump).

The current crisis embroiling the Democratic Party was entirely foreseeable and avoidable. But nothing is inevitable.