He was the most powerful man in the world, the possessor of the nuclear codes. Yet he behaved like a deranged manchild who threw temper tantrums and food against the wall.

That was the tragicomic story told to America last Tuesday at a congressional hearing that had even seasoned Donald Trump watchers lifting their jaws off the floor and speculating that his political career might finally be over.

In two seismic hours in Washington, Cassidy Hutchinson, a 25-year-old former White House aide, told the panel investigating the January 6 attack on the US Capitol that the former president had effectively gone haywire.

She described how Trump knew a mob of his supporters had armed itself with rifles, yet he asked for metal detectors to be removed. She also recounted how his desire to lead them to the Capitol caused a physical altercation with the Secret Service, and how in a fit of rage he threw his lunch against a White House wall, staining it with tomato ketchup.

Trump, who once called himself “a very stable genius”, vehemently denied the allegations but the political damage was done. Infighting and plotting engulfed a Republican party that had hoped the House of Representatives’ committee hearings would pass as a non-event.

Instead they have exceeded all expectations and could prove terminal to Trump’s ambition of regaining the presidency in 2024 if Republican leaders, donors and voters run out of patience and decide to move on.

“Former White House aide Cassidy Hutchinson’s Tuesday testimony ought to ring the death knell for former President Donald Trump’s political career,” said an editorial in the Washington Examiner, a conservative news website. “Trump is unfit to be anywhere near power ever again.”

The column concluded: “Trump is a disgrace. Republicans have far better options to lead the party in 2024. No one should think otherwise, much less support him, ever again.”

Seemingly aware of his growing political vulnerability, Trump is reportedly considering announcing another run for the White House sooner than expected. He has teased the prospect at recent rallies and, according to the New York Times, told advisers that he might declare his candidacy on social media without warning even his own team.

Such a move could have the added impetus of heading off a new star rising in the Republican firmament. Ron DeSantis, the pugnacious governor of Florida, is widely seen as his heir apparent and biggest rival for the Republican presidential nomination in two years’ time. At 43, DeSantis is more than three decades younger and is free of Trump’s January 6 toxicity.

Speaking from Tallahassee, longtime Republican strategist Rick Wilson of Florida said: “I’ve picked up the same rumors that everybody else is hearing that Ron DeSantis’s people are practically picking out curtains in the White House after Tuesday.

“Apparently they feel like this was a phenomenal day for them, that it was a great breakdown of Trump’s malfeasance and they didn’t have to bring the attack – it was brought by one of his former loyalists. If you look at it in terms of the 2024 nomination process, it was a consequential day.”

Wilson, author of Everything Trump Touches Dies, cautioned that the twice impeached former president has been written off countless times before only to bounce back. But Trump has not faced a challenger like DeSantis.

“DeSantis has been very carefully building out a presidential campaign for 2024 to primary Donald Trump, raising money, building relationships, going out there and quietly whispering: ‘He’s crazy, I’m not, I’m younger, I’m smarter, I’m thinner, I’m better looking. I can deliver more for you than the crazy old orange guy,’” Wilson said.

DeSantis certainly has political buzz. Ed Rollins, another Republican strategist, also believes Trump could be done, and has launched a group called Ready for Ron to gather details of DeSantis supporters ahead of an expected presidential bid.

An opinion poll released last week in the state of New Hampshire, traditionally the site of the first presidential primary, showed DeSantis in a statistical tie with Trump among likely Republican voters.

The University of New Hampshire poll found 39% supported DeSantis, with 37% backing Trump – a big swing from October, when Trump had double the support DeSantis did. Former vice-president Mike Pence, who is exploring a 2024 campaign after breaking with Trump post the Capitol insurrection, was in a distant third at 9%.

There have been other clues that Trump’s hold on Republican voters is not what it was. He has seen mixed results for his most high-profile endorsements in key states during this year’s midterm elections, in which DeSantis is seeking reelection as Florida governor.

DeSantis has proved himself a financial powerhouse, raising more than $120m since winning office in 2018. Recent financial disclosures showed his political accounts had over $110m in cash in mid-June.

Trump’s Save America group, meanwhile, had just over $100m in cash at the end of May.

Republican donor Dan Eberhart told the Reuters news agency that three-quarters of roughly 150 fellow donors with whom he regularly interacts backed Trump six months ago, with a quarter going for DeSantis. But now the balance has shifted and about two-thirds want DeSantis as the 2024 standard bearer.

Eberhart was quoted as saying: “The donor class is ready for something new. And DeSantis feels more fresh and more calibrated than Trump. He’s easier to defend, he’s less likely to embarrass and he’s got the momentum.”

And the January 6 hearings are far from over. The six sessions so far have pointed the finger firmly at Trump as the unhinged architect of a failed coup who pushed conspiracy theories about voter fraud he knew to be false and was willing to let his supporters hang his own vice-president.

A survey from the Associated Press-NORC Center for Public Affairs Research found that 48% of American adults say Trump should be charged with a crime for his role. The crisply presented hearings would have been enough to bury any other politician for good.

Political scientist Bill Galston, a senior fellow at the Brookings Institution thinktank in Washington, said: “If the testimony stands as delivered, many Republicans will begin to ask themselves whether it wouldn’t be preferable to find a candidate with Mr Trump’s views but not his vices.

“And, of course, there is such a candidate waiting in the wings. Tuesday’s hearing was a ‘Ron DeSantis for president’ rally because it underscored the risks of sticking with Mr Trump for a third consecutive presidential election.”

Galston, a former senior policy adviser to President Bill Clinton, described DeSantis as “the distilled essence of what the post-Reagan Republican party has become. In addition, it’s clear to the Republican base that, like Trump, he’s a fighter. Like Trump, he is not at all deterred by liberal criticism.”

Some believe the cumulative effect of the January 6 hearings could be enough to persuade many in the “Make America great again” base that, even while they remain devoted fans of Trump, he is no longer the pragmatic choice to oust Democrat Joe Biden from the Oval Office.

“The big question for Republicans moving forward is: do they want to carry this baggage of Trump into 2024?” said the director of the Center for the Study of Politics and Governance at the University of Minnesota, Larry Jacobs.

“When you’re battling to win over independent voters and when you’re going to be handed a platform that could very well present a referendum on the insider party, the Democrats, it doesn’t make sense even for a lot of Republican Trump supporters. Trump and his influence and his future prospects are fading fast.”

But the populist-nationalism that the ex-president branded “America first” does look set to survive him, Jacobs added.

“In the primaries, there’s going to be a battle of who can carry Trumpism without Trump and that’s going to be ethnic nationalism, attacks on the liberal cultural tilt of this moment,” Jacobs said. “You go to a Trump rally, a lot of those lines are going to be evident.”

For Democrats, it may be a case of being careful about what you wish for. DeSantis was a relatively obscure congressman when Trump endorsed him for Florida governor in 2018 and has proven a worthy disciple, sparring with everyone from journalists to Disney to what he calls the “woke left”.

After the coronavirus pandemic took hold in 2020, he relaxed restrictions on businesses and schools in defiance of federal guidelines and overruled local officials who sought to preserve mask mandates.

DeSantis has also enacted numerous conservative bills with the help of Florida’s Republican-controlled legislature, including an election “police force” dedicated to investigating alleged voter fraud, new voting limits and banning teachers from discussing gender identity with young children – which critics decry as the “don’t say gay” law.

He also effectively commandeered the redistricting process from Florida’s state legislature, vetoing their congressional map and substituting his own proposal that eliminated two majority-Black districts while delivering four additional seats to Republicans.

Some fear that, as president, DeSantis would represent Trump 2.0 – a refined, purified version without the incompetence, more efficient and ruthless and able to get things done.

Wilson, the longtime Republican consultant and Trump critic from Florida, commented: “Ron DeSantis in Florida has accumulated enormous power. He has taken power away from the legislature. He is attempting to take power away from independent colleges and universities and to literally replace governance at every institution in Florida from top to bottom with the governor’s office.

“I grew up in a time where Republicans thought a hyper powerful executive was not a great thing but Ron DeSantis has a very different opinion of executive power and he, as president, would engage in its use at a scale that would be dangerous for the country at a lot of levels.”

The first nominating contests for the 2024 election are more than 18 months away, and the long term impact of the January 6 hearings remains uncertain. Lou Marin, executive vice president of the Florida Republican Assembly, does not think they will change minds. “People who are paying attention realize that it’s a kangaroo court,” he said. “They need to move on and start doing their job instead of wasting taxpayer dollars.”

DeSantis will also be wary of peaking too early and keenly aware that Trump, who famously boasted that he could shoot someone and not lose any voters, remains his party’s most popular figure. A Harvard CAPS-Harris Poll this week found 56% of Republican voters said they would back the former president – well ahead of DeSantis on 16%.

Former Republican National Committee chairman Michael Steele said: “A lot of people want to put a tombstone on the grave but Donald Trump is still above ground. He’s still walking the earth and has a lot of political clout with a lot more people inside the party than folks may want to admit.

“Those bridges are in front of us. We haven’t come to them yet to see exactly what these extra revelations will now present in terms of further chiseling away Donald Trump’s hold on the party.”

Some Democrats argue that DeSantis would be preferable because, unlike Trump, he would not threaten the foundations of America’s constitutional democracy.

But Steele warned: “Who’s the better thief, the one who breaks the window to get into your house or the one who’s craftily picked the lock? DeSantis knows how not to trip the alarm system.”