IN TRUCKS, boats and buses, protesters streamed into Bangkok for a non-stop rally that was billed as a “people's war against the elite”. By March 14th the crowd, all wearing bright red and brimming with elation, had passed 100,000. On the stage, speakers railed against the government and its royal and military enablers. Banners read “No Justice, No Peace”. Another bruising round in Thailand's protracted power-struggle was under way, with no clear end in sight.

By mid-week the red shirts seemed no closer to their goal of forcing out the prime minister, Abhisit Vejjajiva, and forcing new elections. The army stands squarely behind Mr Abhisit, who took power 15 months ago by a parliamentary fix and remains the hero of Bangkok's myopic monied classes, as well as the yellow-shirted protesters who support the status quo. But in a one-man, one-vote democracy, the have-nots hold the key to success.

Thailand's twice-elected and now fugitive former prime minister, Thaksin Shinawatra, understood this well. He has refused to keep quiet since the army ousted him in 2006. A court ruling on February 26th to seize $1.4 billion of his fortune has only made him angrier. Many red shirts consider Mr Thaksin to be the country's true leader and, despite his enormous wealth and privileged life, make common cause with him.

Ruling-party politicians complain that the lowly red shirts are paid proxies and do not represent mainstream opinion. They bat away the idea that an election may be the only way to prove their point, arguing that an orderly vote is impossible amid the tumult. Most of all, they blame Mr Thaksin for the uproar.

But there is another figure in the political landscape to consider: King Bhumibol Adulyadej, at 82 the world's longest-reigning monarch. At the rally site, a giant spotlit portrait of him gazed down impassively on the red-shirted crowds. To Thailand's royalist movement the monarch is the nation's father, and the “fighting children” on the streets are a source of distress to him. Some fear that Thailand's troubles may be thwarting King Bhumibol's full recovery from the respiratory illness that has kept him in hospital since September.

But it is precisely because “father” is on his way out that his “children” are fighting. The death of a monarch is always a moment of national drama and self-reflection. Thais feel a dread of it. Few have known any king other than Bhumibol, who ascended in 1946 to an institution that had slipped into irrelevance. As military rule gave way to a semi-functional democracy, the palace served as a respected power-broker. But its legitimacy depended on the charisma of King Bhumibol and the stealth of his courtiers.

The palace insists that the king is alert and active. But Thais already fear a destabilising royal succession. Investors are especially worried, and the more so because lèse-majesté laws discourage frank talk about it. When a large Thai brokerage polled fund managers about political risk factors in 2010, 42% of respondents chose what the brokerage describes as “a change that cannot be mentioned”. Rumours of King Bhumibol's death last October sparked a two-day equities sell-off and a furious government witch-hunt for rumour-spreaders. The real thing is likely to outdo that rout.

Thailand has already endured four years of turmoil. The death toll has been low so far, but the rage unleashed last April, when red shirts fought the army in Bangkok, was a glimpse of how deep passions run. Splits within the army itself are starting to appear. Even if fears of all-out civil war seem overblown, it is reasonable to expect more years of political confrontation and paralysis.

The crown itself should pass smoothly. The designated male heir is Crown Prince Maha Vajiralongkorn, aged 57, and there is not much scope for doubt about his claim. A long mourning period, perhaps six months or more, will allow a pause in the political dogfight. Some protagonists may come to their senses and seek a compromise. The death of King Bhumibol would also signal a generational shift in Thailand: younger voices could start to be heard.

But this king will be a most difficult act to follow, and Prince Vajiralongkorn is already widely loathed and feared. Most Thais try not even to think about his accession. “This reign ends. And then, nothing,” says an academic. The next ruler must fill the shoes of a beatified icon whose achievements have been swathed in a personality cult. The role of a crown prince in an era of great longevity and public scrutiny is tough anywhere. In Thailand it verges on the impossible. “How do you follow someone who walks on water?” asks a senior Western diplomat.

Doubts about the prince

This conundrum is a familiar one. King Vajiravudh, Rama VI, who assumed the throne in 1910, had a rough ride in the shadow of his father, King Chulalongkorn, a vigorous moderniser. Even before he ascended to the throne he was tainted by palace gossip of alleged bad behaviour, according to Thongchai Winichakul, a Thai historian at the University of Wisconsin. Vajiravudh was a “fantastic poet and playwright” but an also-ran monarch who was eclipsed by his exalted predecessor. “The royals shot themselves in the foot,” Mr Thongchai told a recent public seminar.

His successor, Prajadhipok, Rama VII, fared worse. A bloodless 1932 coup ended absolute rule and nudged the Thai monarchy towards the margins. Prajadhipok fled to exile in London and abdicated in 1935, deepening the drift. He handed over to Rama VIII, King Bhumibol's elder brother, who died in 1946 after a mysterious shot to the head. Bhumibol was proclaimed king the same day, and promptly returned to Switzerland to complete his studies.

In 1926 Prajadhipok had written frankly about the shortcomings of dynastic rule. In a letter, he wrestled with the clash between a society in flux and the law of hereditary kingship, a clash that seems to hang over Thailand today. The king's rule was one “of great difficulty” as public opinion had turned against absolute rule. He fretted over who might be coming next. “Some sort of guarantee must be found against an unwise king,” he wrote.

Nearly a century on, no such guarantee exists. Instead, Thais are faced with the prospect of Prince Vajiralongkorn, a career army officer and fighter pilot, who has already assumed many ceremonial duties from his father. Largely absent in recent years on jaunts around Europe, he is now back in Thailand and in the public eye. The signals are loud and clear. Two weeks after King Bhumibol's birthday speech, the Bangkok Post ran a stiff, respectful profile of him under the headline: “King in Waiting”.

For Thais used to King Bhumibol's virtues, which include monogamy, Buddhist piety and old-fashioned thrift, the crown prince is a poor substitute. Salacious stories of his private life are daily gossip. A video circulated widely in 2007 showed his third wife, known as the “royal consort”, at a formal dinner with the prince in a titillating state of undress. Diplomats say Prince Vajiralongkorn is unpredictable to the point of eccentricity: lavishing attention on his pet poodle Fu Fu, for example, who has military rank and, on occasion, sits among guests at gala dinners. In the 1980s his rumoured ties to the criminal underworld, which he denied in a newspaper interview, inspired the gangster nickname of “Sia O”.

In contrast, Princess Sirindhorn, his sister, enjoys a saintly image as a patron of charity. Many Thais are praying for an eleventh-hour change that installs her on the throne. Some army and palace factions are said to favour the princess as the next ruler. Other possibilities aired in recent years are a jump to Prince Vajiralongkorn's children, such as his youngest, Prince Tipangkara, with a regent, perhaps Princess Sirindhorn. The leaked video was presumably a bid to discredit the prince and push other options. So far, however, King Bhumibol seems to have made up his mind that Prince Vajiralongkorn will succeed him.

Vajiralongkorn, meddling already

Paul Handley, the king's unofficial biographer, whose book is banned in Thailand, thinks there is a tiny possibility that King Bhumibol could decide on his deathbed to disinherit Prince Vajiralongkorn. That would require a written command. Life in exile in Europe might suit the prince, who would not want for money or diversions. Inevitably there are other, bloodier, predictions of how he might be removed from the succession. This might explain why soldiers in his personal guard are not allowed to wear guns in his presence.

One reason why Prince Vajiralongkorn is distrusted in military circles is his past association with Mr Thaksin, who was ousted by a military coup in 2006. Mr Thaksin, a telecoms billionaire turned populist politician, was said to have lavished money on the prince. That may have been the real reason for the coup, which appeared to have the blessing of Prem Tinsulanonda, the chairman of the Privy Council and thus the king's chief adviser. The fact that Mr Thaksin, who is living in exile in Dubai, is still in contact with the prince is deeply troubling for those same royalists. In a recent interview with a British newspaper, the former prime minister lavishly praised the heir to the throne.

Nobody knows what kind of ruler Prince Vajiralongkorn would be. Sulak Sivaraksa, a veteran royal observer and social activist, says that the prince has matured during his third marriage and is more respectful of others than in the past. Others say that he is still easily bored by royal duties, unlike Princess Sirindhorn, who lives for them. Above all, say royal watchers, he needs able courtiers to steer him through the political pitfalls ahead. Many believe that Prince Vajiralongkorn will replace the Privy Council with his own men. For senior courtiers who have served the king and look askance at his successor, an exit will be welcome. But the new men “will definitely not have the calibre” of the current crop, says a foreign scholar.

Mighty but clumsy

A taste of this came last year when Mr Abhisit, the prime minister, tried to reshuffle the police force. His choice for police chief was blocked by members of his own team, including Nipon Prompan, an aide to Prince Vajiralongkorn, who lobbied for another candidate. A “powerful and mighty” backer was reported to be pushing the second man, a former head of national intelligence under Mr Thaksin. Mr Nipon later resigned from the cabinet. Mr Abhisit was unable to confirm his man, who is currently acting chief. The row exposed Prince Vajiralongkorn's clumsy meddling. It also provoked apoplexy among King Bhumibol's courtiers, says a palace source. Prince Vajiralongkorn was told that “we don't do things like this,” the source says.

In fact, the palace has long patronised loyalists in the army and bureaucracy. This is how power operates in Thailand. What made Mr Thaksin such a threat to the palace was his determination to exert similar control. In turn, Prince Vajiralongkorn is itching to meddle in the annual autumnal shuffle of senior jobs in the armed forces and extend his support base, says a senior Asian diplomat. How far he succeeds may determine how long he lasts. Another possibility is a royal pardon for Mr Thaksin so that he can return to manage state affairs for the new king. This would delight the red shirts. But it would appal Bangkok's elite and split the army. As for courting public support, this seems far-fetched. The prince knows he is unpopular, says a political acquaintance, but “he doesn't care.”

One way out of this predicament would be to shrink the Thai monarchy back to its previous size. Top-down reform of the institution is more palatable than a push from below with republican overtones. Under King Bhumibol its stock has fallen already from its zenith in May 1992, when he could order a military dictator to cease and desist. Recent years have exposed the limits of his powers. In 2008 the king was unable to stop the People's Alliance for Democracy from sowing chaos in his name. “We expect too much of him,” sighs a senior courtier.

Clearly Thailand needs a new equilibrium. Some fear that the power vacuum left by an enfeebled monarchy will be filled by the army, which is already the steel behind the palace's gilded façade. But the generals who seized power in a coup in 2006 did a dismal job of running the country, and had to return power to the voters 15 months later. Business families do not want a repeat performance, and would prefer to have politicians and professionals in charge. Several banned MPs, some hoping to lead parties, will re-enter the field in 2012. But the rules of the game will need to be reset.

Some might argue that King Bhumibol shares the blame for the failure of democratic institutions to take root in Thailand. Relying on “a few good men” and the army to steer the country has left it in the lurch, says Mr Handley.

It is a sad twilight for the monarch. Thailand was once an outpost of freedom in a fairly repressive region. Scrappy politics did not choke rapid economic growth, as the bureaucrats kept a steady hand on day-to-day management. In the 1990s Western rights activists hoped that the dynamism of Thai civil society might spread to neighbouring countries. Instead, some now see Thailand as a cautionary tale of a botched democracy.

That may be too harsh. Thailand's rival red and yellow mobs disagree about democracy, but both want a fair political system. To measure tolerance, the California-based Asia Foundation last year surveyed Thais about their views. It found that 79% of respondents would allow unpopular political parties to meet in their area. Only 6% said that they would stop seeing a friend who had joined a rival party. These are healthier figures than in other Asian democracies. Almost everyone agreed that democracy was the best form of government, though 30% would accept authoritarian rule in certain circumstances.

Thailand has not yet given up on democracy. But taking stock of its troubled politics should include talking about the crown. Of course, it is distasteful—and inauspicious, Thais believe—to speak of King Bhumibol's death. But it is unavoidable. The stakes are too high. Respect and fear have kept a lid on the debate. Anyone who speaks out of turn in Thailand risks arrest under the lèse-majesté laws or a new, equally nasty computer-crimes law. Several people have been prosecuted for defaming the king and his family, including an Australian jailed (until freed by a royal pardon) for writing a novel that contained an unflattering depiction of the crown prince.

Behind closed doors, a spirited debate goes on over the fate of the monarchy when the king dies. An old prophecy holds that the Chakri dynasty will last only nine generations. King Bhumibol is Rama IX. Republican voices are rising to the surface—unreported in Thailand's pliant media. The Bangkok Post struck a typical tone of pride and menace in its birthday eulogy for the king in December: “The Thai people's love for his majesty is so ingrained in the national psyche that to declare otherwise is unthinkable.”

Gagged and flagging

Within palace circles, however, there is a dawning realisation that change is coming. Senior royalists know that King Bhumibol's charisma and influence will not easily transfer to his successor. This is the crux of Thailand's royal impasse. And King Bhumibol knows it, says Mr Sulak. As he puts it, the king “would like to see that the next reign will not be bloody.”

To this end, King Bhumibol recently asked three trusted emissaries to present ideas for reforming the institution, according to Mr Sulak. One emissary asked for Mr Sulak's advice, explaining that the findings would be for the king's eyes only. Mr Sulak replied that the palace must be transparent about its finances, including some $35 billion in assets managed by the Crown Property Bureau, decouple itself from the army and open up to public criticism. Only by becoming a European-style figurehead can a future monarch survive, he argues.

Preserving the tree

Mr Sulak has often been accused of lèse-majesté. He insists that he is a monarchist at heart. “To pull down the tree is easy. But I think it's better to preserve it,” he says. Such steps just might rescue the Chakri dynasty. But a radical rethink seems unlikely. Allowing opponents to attack an insecure ruler could quickly escalate. Under King Bhumibol the silencing of opponents has been controversial, but many tolerate it out of respect. Prince Vajiralongkorn can expect no such leeway.

What might a diminished monarchy look like? Thailand may not be ready for such a thing. In Spain, the palace's annual household budget of €9m ($12m) is audited by the government. Norway puts its royal accounts on a website. It is impossible to find out how much Thailand's jet-setting royals spend. Japan may be a better model, as a respectful national press keeps its distance.

It took defeat in the second world war and an American occupation to curtail the powers of Japan's emperor. Other royal houses were whittled down to size by assertive parliaments. This happened in Thailand in 1932, but was later reversed under King Bhumibol. Clearly, some constitutional fixes would be needed to shrink the sovereign's role. But power in Thailand flows along patronage networks that start with the king. That is why elected ministers who care about their careers are continually looking over their shoulders for signals from the palace. Mr Abhisit attends so many royal ribbon-cuttings that it is hard to imagine how he finds time to govern, says a senior Western diplomat.

Royal censorship has kept much of this debate under wraps. That is a pity. King Bhumibol famously said in 2005 that he was not above criticism. But not many are ready to test that. Though the internet is humming with opinions, the taboo still stands. And because the country has never had a chance to talk openly, people cannot prepare themselves for what may be a rough road ahead.