Both Biden and Trump are in trouble, but who will blink first?

The two major US political parties – the Democrats and the Republicans – are perennially in upheaval. That's by design in a system that funnels all major political inputs into two giant, uneasy coalitions.

But the two party leaders are looking unusually weak these days. In different ways, Donald Trump and Joe Biden aren't inspiring much confidence.

Mr Biden's is the more straightforward case. He and his fellow centrists are still in charge of the Democratic Party, even though they face persistent challenges from a left wing that wants to take control. Like many first-term presidents, Mr Biden is facing a second year of misery. His poll numbers range from bad to abysmal, and despite his deft handling of the Ukraine crisis, it's still "the economy, stupid" that shapes the national mood.

First-term presidents' parties typically lose ground in their first midterms. Mr Biden may face a particularly large setback, because his party already has little room to manoeuvre in Congress. The persistence of significant inflation and the growing threat of a potential recession explain the distinctly sour mood of the country. It's looking like a grim November for the Democrats.

However, his opposite number, Mr Trump, appears, if anything, to be in even bigger trouble. It's remarkable that he has been able to maintain a tight grip over his party despite his 2020 presidential election defeat to Mr Biden, although that's partly because he has convinced most Republicans that he didn't actually lose but was cheated. But as the Republican primaries for the November election are demonstrating, that grip is loosening considerably.

His spectacular comeuppance in Georgia last week was stunning. David Perdue, his anointed candidate, was demolished by incumbent governor Brian Kemp by more than 50 percentage points. Even worse, Georgia Republicans also re-nominated Secretary of State Brad Raffensperger. Both men rebuffed Mr Trump's claims about massive fraud in Georgia's 2020 election, and Mr Raffensperger did so with public derision and contempt. Mr Trump's effort to take vengeance on these alleged turncoats was of no interest to Republicans in Georgia.

Mr Trump's efforts to play the wrathful kingmaker have had, at best, mixed results. The Georgia humiliation was entirely self-inflicted. There was no rational reason for the former president to make state-level primaries de facto referendums on himself and his ridiculous fabrications about the 2020 vote. While most Republican candidates won't criticise Mr Trump or challenge his "big lie" about that election, it's clear that voters can distinguish between candidates who appeal to them and those he anoints. His cult of personality is in trouble.

It should be good news to him that his style of politics appears to be transferable and to have a life of its own. But it's evidently, and unsurprisingly, not. While he is still easily the most popular Republican figure, it's almost certain that Mr Trump would face some sort of opposition, and possibly a potent and credible one, if he seeks the 2024 presidential nomination.

Potential challengers include Florida Governor Ron DeSantis. Indeed, Mr DeSantis appears to be slowly constructing an American analogue to Viktor Orban's Hungarian "illiberal democracy" in Florida with elements of authoritarianism and hints of fascism. Mr DeSantis refuses to say whether he would challenge Mr Trump for the nomination or not. And the former president has not formally announced another campaign for the presidency.

But it is becoming increasingly clear that if he cannot move past re-litigating the 2020 election, he will not be a viable national candidate in 2024, even if he can win the party nomination. A group of prominent Republican leaders have banded together to oppose what they call Mr Trump's "revenge tour" of primary elections, and are plainly looking for alternative leadership.

Time is not on Mr Trump's side, particularly if he continues to obsess about 2020. But it may be on Mr Biden's. There is a strong pattern of Americans electing a president, then defeating his party in the first midterms, especially in the House of Representatives, and then re-electing him for a second term. This pattern of divided government applied to Ronald Reagan, Bill Clinton and Barack Obama, while George W Bush's first midterms were held in the aftermath of the 9/11 terrorist attacks and its atmosphere of national unity.

So, Mr Biden’s chances of re-election may be better than many assume at present. Arguably the biggest challenge he will face is his age. He was 78 when he was elected as the oldest US president in history. Mr Trump, however, was the third oldest at age 70.

The American political system doesn't only suffer from structural dysfunctions, particularly anti-democratic elements that have yielded many dangerous manifestations of minority rule. It's also beset by an unhealthy level of gerontocracy, the rule of the elderly. It's not just Mr Biden and Mr Trump. Most of the senior leadership in both parties in the House and Senate are remarkably advanced in age. That's not necessarily a disaster, but it does demonstrate the undue advantage incumbents generally enjoy and, more strikingly, the noticeable lack of talent in the two, or in some cases even three, generations labouring to succeed them.

Mr Trump already defied expectations by winning the Republican nomination and then the presidency in 2016, and by remaining the dominant Republican despite his 2020 defeat. But the signs that his ascendancy may be ebbing are clear. Mr Biden's real test, meanwhile, will come after the midterms, particularly if, as seems likely, his party suffers a major defeat. That would almost certainly initiate a concerted and bitter attack from the left on his centrist leadership and policies.

Both the Republican and the Democratic leaders are old enough that their health is an issue, and, although it's obvious that both men are fully in control of their wits, both are frequently accused of being senile. Yet, Mr Biden has a huge advantage. He is in the White House. And that gives him leverage Mr Trump doesn't have to fend off internal party critics, battle Republicans and persist in shaping a forward-looking agenda. He's got enormous power.

Mr Trump not only lacks such authority, as ever he's his own worst enemy. As long as he makes dozens of state-level elections de facto referendums on his leadership and, especially, remains fixated on re-litigating 2020, his influence on national, and even Republican, politics can only continue to decline.