The first day in a new job can be daunting for anyone. "Where is the coffee machine? Will my boss be a nightmare?" we may find ourselves asking.

Spare a thought then for 73-year-old King Charles III (millions in reportedly tax-free inheritance and lifetime job security notwithstanding) as he steps into possibly the most formidable shoes on Earth: the smart, sensible, well-worn heels of the late Elizabeth II.

The new king inherits the throne from a monarch credited even by detractors as a skilled public servant who understood her specific role in politics: to remain above the fray.

Elizabeth enjoyed a 75% approval rating among the British public, compared with 42% for her son, a YouGov poll earlier this year showed.

A lot is riding on Charles's performance. The family has been beset by scandals of late.

The king's brother Prince Andrew settled a sexual assault lawsuit this year and has more or less withdrawn from public life.

Prince Harry stepped away from his royal duties in 2021 and moved to the US with his wife, Meghan Markle, amid a public family rift.

The monarch's own reputation never really recovered from his messy divorce from Diana Spencer, Princess of Wales, who died in a car crash in 1997 but remains hugely popular.

King's 'lackluster' personality

The outpouring of public grief following the queen's death may suggest that the monarchy is in good standing.

But the academic Pauline Maclaran, author of "Royal Fever: The British Monarchy in Consumer Culture," doesn't believe it's that simple.

"Support for the queen does not necessarily transfer to the monarchy as an institution," said Maclaran, a marketing professor at Royal Holloway, London University.

Backing for the monarchy, though still high, plunged dramatically from 75% in 2012 to 62% a few months ago, according to pollsters YouGov.

Maclaran said major risks for Charles included his lackluster popularity and his reputation for interfering in public business.

"People have long expressed the fear that Charles could meddle too much in politics," she said. As Prince of Wales, Charles was chastised for writing a string of letters that allegedly compromised his impartiality.

Perhaps an even bigger risk, Maclaran said, is that Charles will lead the monarchy as a white, heterosexual, privileged male at a time of growing awareness of identity issues and of increased awareness of the colonial past.

"The next in line is also a white male and the next after that," she said, referring to Charles's son Prince William and Prince George, William's first child.

There are also open questions about the Commonwealth and calls for reparations for colonial-era wrongs, Maclaran said.

Indeed, the first place it could all start to unravel for Charles is the 14 Commonwealth countries that still have the British monarch as their head of state (out of 56). Barbados bid adieu and became a republic last year; others could follow suit.

The prime minister of the West Indies nation of Antigua and Barbuda told British broadcaster ITV last week the he planned a referendum on the matter within three years. Jamaica has expressed interest in a similar move. The leaders of Australia and New Zealand also back the move in theory, though they don't seem to be in any rush.

Republicans sense their chance

What about within the UK? One organization that sees the accession as a potential opportunity is Republic, an anti-monarchy campaign group.

"A proclamation of a new king is an affront to democracy, a moment that stands firmly against the values most of us believe in, values such as equality, accountability and the rule of law," spokesperson Graham Smith said in a statement published last week.

Though careful to pay respects to the queen, Republic has been preparing for the crown to change hands for a while, noting the trend of declining public support.

"The queen is undeniably the most popular member of the Royal Family. So when she's no longer on the throne ... King Charles is not going to be in a position to turn that around. He's going to lose more support," Smith said in a conference talk back in June.

Despite Smith's optimism, the UK's republican movement clearly faces an uphill struggle.

The most fertile ground for the cause is likely Scotland. This year, a poll by the UK-based think tank British Future found that only 45% of Scottish voters back the monarchy. During Charles III's proclamation as king, protesters booed on the streets of Scotland's capital, Edinburgh.

Nonetheless, thousands in Scotland turned out to pay their respects to Elizabeth, who was famously fond of the country. Even the ruling Scottish National Party, which wants to see Scotland become independent, has made clear it would keep the British monarch as its head of state should the country leave the UK. That position remains unchanged in the wake of Charles's accession, said Scottish Deputy First Minister John Swinney, according to Scotland's The Herald newspaper.

Monarchy established as brand

Could Charles's performance ever be so bad that it pushes Scotland, or even the entire UK towards abolishing the monarchy?

"I don't think so," branding expert Maclaran said, adding that she believes the new king is aware of the risks and will be on his best behavior.

The approach of the royals will be to push the "collective brand" of the broader family, she said.

"Charles can't do this on his own and he's aware of that," she said. He will work closely with the more popular William and Kate and also his queen consort, Camilla, in order to "have women playing strong roles."

Maclaran thinks Charles has gotten off to a great start in his first appearances, addressing known public fears head on. "But this is the honeymoon period. People are feeling emotional," she said.

Republicans such as Graham Smith shouldn't underestimate their opponent.

The monarchy is "very image-conscious" and "very good at adapting," Maclaran said. "At the end of the day, the monarchy is a very sophisticated institution."

Edited by: Kate Hairsine