BANGKOK, Aug. 29 — Sounding desperate, Thailand’s harried leader, Thaksin Shinawatra, wrote to President Bush last spring with what sounded like an S O S Thai democracy, he said, is under threat.

“Key democratic institutions, such as elections and the observance of constitutional limitations on government, have been repeatedly undermined,” he wrote in a letter reproduced in the Thai news media.

He had been forced by public pressure to give up his office in April, he explained, but was staying on as what he calls a caretaker prime minister.

Mr. Bush sent a friendly, noncommittal reply.

Since then things have only gotten worse for Mr. Thaksin as court rulings go against him, allies desert, his party faces a possible ban by the courts, and an election scheduled for October that he may see as his lifesaver appears about to recede further into the future.

Some say this is the endgame in a campaign against him that has included huge street demonstrations and an opposition boycott of an election that he won in April, which was subsequently annulled in court.

The question here is, who is threatening democracy and undermining constitutional limitations on government: the people who have taken to the streets and turned their backs on an election, or Mr. Thaksin himself?

His critics say Mr. Thaksin has so eviscerated democratic institutions and processes in his five years in power that they had no other means of opposing him or protecting the Constitution.

In a rationale that echoes the one given in the Philippines for repeated “people power” uprisings, they say, in effect, that they must destroy democracy in order to save it.

“It’s not true that Mr. Thaksin represents genuine democracy and overthrowing him in the streets is unacceptable,” said Thitinan Pongsudhirak, a political scientist at Chulalongkorn University. “I think democracy is nuance, it’s subtle and has to be contextualized. Just because you have someone coming along and winning elections is not tantamount to having democratic rule.”

Mr. Thaksin is an election-winner, the biggest in Thai history. He still has the overwhelming support of the country’s poor and rural voters and would almost certainly be re-elected in any new ballot.

But that would not solve the country’s problems, or end the current impasse, his critics say.

“Mr. Thaksin says he plays by the rules, but he’s the one who broke the rules most of the time,” said Kavi Chongkittavorn, a political commentator at The Nation daily newspaper. “I think democracy means a lot of things. It doesn’t just mean elections; it also means checks and balances, it means transparency, it means how you use your powers, it means you are accountable as a leader. On these things, Mr. Thaksin does not have a good record at all.”

There is some excitement here about replicating Philippine “people power,” but if the Philippines experience has anything to offer Thailand, it is a warning.

Precedent is powerful, the Filipinos found; democracy is fragile, and once the fire of popular putsch is lit, it can smolder for years, then burn down another government. Since the original popular uprising in 1986, there have been both a “People Power 2” and a “People Power 3” against democratically elected presidents, one of which succeeded.

The response to this in both the Philippines and Thailand is that their democracies are young and imperfect, and that their self-regulating mechanisms cannot always be relied on as they are in more mature democracies.

In the Philippines, for example, former President Joseph Estrada was ousted in 2001 by a popular uprising after a constitutional impeachment process failed because of corruption in the legislature.

In Thailand, Mr. Thaksin’s manipulation of democracy has been as thorough and direct as anything the Philippines has seen in recent years.

He came to power in 2001 with the country’s first outright majority in Parliament, a result of a new Constitution, passed in 1997, that was meant to create more stable governments.

Once in office, his critics say, Mr. Thaksin used his electoral mandate as a cover to begin weakening the young Constitution’s checks and balances that limit his power.

He packed his allies onto independent commissions on elections and corruption, the constitutional court and the Senate, as well as the military leadership. He undermined civic organizations, intimidated the news media and monopolized television, and used his overwhelming mandate and his control over government institutions to crush political opposition.

His critics say he has also used his office to enrich himself, his family and favored businessmen. The chief spur to the uprising against him was the sale by his relatives of the Shin Corporation, the family’s telecommunications empire, to a Singaporean company for $1.9 billion tax free, taxes that otherwise would have gone into the national treasury.

In a potentially dangerous tactic, he has played on divisions between the urban middle class, which has risen to challenge him, and the rural poor who are his base.

As his struggle for political survival intensifies, some military and government officials have warned about the possibility of violence before an election, which is likely to be delayed after a court dismissed an election commission that favored Mr. Thaksin.

In recent days fistfights have broken out between supporters and opponents during his public appearances. A report of a bomb plot against him has raised fears of larger-scale violence or of a declaration by Mr. Thaksin of a state of emergency.

His aggressive use of power and the uprising against him have set the country on an unpredictable course, stretching the limits of the Constitution and, as Mr. Thaksin said, threatening democracy.

“My fear is that we will emerge out of this crisis many months from now so bruised and so bloody that we’ll be unrecognizable,” said Mr. Thitinan, the political scientist.

A question many opponents of Mr. Thaksin — or of Philippine leaders — fail to ask is what would come next if their elected leaders are overthrown, sidestepping the democratic process.

In the Philippines, President Gloria Macapagal Arroyo is herself the product of people power, moving into the presidency when Mr. Estrada was forced out. She has disappointed the public, and so she too has become the target of people who want to push her from office.