Thais usually celebrate Songkran, the country’s traditional new year festival, by tossing water and visiting Buddhist temples. Wealthy businesswoman Yingluck Shinawatra marked the April holiday by flying to Dubai in the United Arab Emirates to visit her fugitive older brother, Thailand’s ousted former prime minister Thaksin Shinawatra.

“He is my brother . . . so I have to pay respects to him,” the 43-year-old executive said in an interview.

After returning to Bangkok, Yingluck announced that she would quit her job as head of SC Asset Corp., a successful property company majority-owned by her relatives. She then set out to revive another family enterprise: running Thailand, America’s oldest ally in Asia.

Advised by her brother — who was toppled from power in a 2006 military coup — Yingluck is the front-runner to become Thailand’s next prime minister after elections July 3.

Widely seen as a referendum on Thaksin, the upcoming vote is reviving passions that a year ago turned central Bangkok into a war zone when the army moved in to dislodge his “red shirt” fans from the city’s ritziest shopping district.

Although initially dismissed as a novice, Yingluck has run a skillful campaign, and the prospect of her taking the job snatched from her brother has raised the question of whether, as in the past, Thaksin’s enemies might try to overturn an election result that they don’t like through military intervention or judicial maneuvers.

“I want to see the positive side and I don’t want that to happen,” said Yingluck, who was selected last month to head a list of candidates put forward by the pro-Thaksin opposition party, Pheu Thai, which means “For Thais.” She urged other countries to follow the elections and make sure that authorities “respect the Thai people’s decision. If they don’t respect [the results], democracy won’t come back in Thailand.”

The looming showdown has put Washington in a bind. It supports democracy but worries that the elections could presage yet more instability in this economically vibrant but politically fractured Southeast Asian nation. “It’s a very complex period in Thailand,” Kurt Campbell, the U.S. assistant secretary of state for East Asian affairs, said in Washington late last month.

Thailand has had 18 coups, 23 military governments and nine military-dominated governments since it became a constitutional monarchy in 1932. But the military, which holds regular exercises with U.S. forces, has shown little appetite for a repeat of last year’s bloodshed, in which at least 90 people died, and has vowed to stay out of the upcoming elections.

Still, Thaksin’s opponents last week launched a legal challenge to try to derail his sister’s campaign. They accused her of lying to Thailand’s Supreme Court to help her brother retain a portion of his assets. Yingluck’s party responded by filing a defamation suit.

Amnesty question

Revered by his supporters, particularly in Thailand’s poorer regions, but loathed by conservative forces in the military, political elite and royal court, Thaksin is such a divisive figure that his sister has sought to balance appeals to the family’s devoted political base with assurances that she is not seeking revenge. In carefully scripted speeches and media interviews, she has mostly stuck to platitudes.

A Western diplomat with long experience on Thailand likened her to Sarah Palin, “but with the sense to keep her mouth shut and avoid gaffes.” She declined to take part in a debate with her main opponent, Thailand’s current prime minister, Oxford-educated Abhisit Vejjajiva, and spent her time touring the country, wooing voters with her photogenic good looks, soothing tone and expansive appeals to both Thailand’s poor and its business community.

Speaking at Pheu Thai’s Bangkok headquarters, Yingluck said she had no immediate plans to pursue amnesty for her brother, who was convicted of corruption in 2008 and is also wanted in Thailand on terrorism charges relating to a wave of arson attacks and violence during the army’s assault last year on anti-government “red shirt” demonstrators. Thaksin, from his refuge in Dubai, has dismissed both cases as politically motivated.

A former tycoon who made billions of dollars in telecommunications and other ventures, Thaksin first came to power in 2001 with a big majority and, as Thailand’s self-styled “CEO prime minister,” shook up the bureaucracy and guided the country to an economic boom. But he alienated the traditional establishment and parts of the middle class by reaching out to rural voters scorned by many Bangkok elite and by displaying increasing and sometimes brutal intolerance of those he viewed as enemies.

Many Thais, said Yingluck, want Thaksin “to come home because he did many good things for the country.” But she added: “We have to move the country forward, to unite Thailand. Amnesty will be after that. If we do apply an amnesty, Dr. Thaksin will get the same treatment as any other” in a possible general pardon to reconcile rival camps.

Similar thinking

Yingluck, a mother of one who studied in Kentucky, said she speaks with her brother, who is 18 years her senior, by telephone “quite often” but denied that he is orchestrating her campaign. She said that Thaksin “gives some good ideas” but that “I decided myself” to run for election and “he supported this.”

Her opponents scoff at such assertions. “Why did she go into politics?’’ said Kraisak Choonhavan, deputy leader of the ruling Democrat Party. “She is probably one of the richest women in Asia. She has it all, so why go through this? Because big brother asked her to.’’

Yingluck’s campaign leaflets boast of Thaksin’s role: “Thaksin Thinks, Pheu Thai Does,” reads a party slogan. Thaksin, in a recent interview with Australian television, described his sister as his “clone.”

Yingluck said this doesn’t make her Thaksin’s puppet but means only that they share “the same logical thinking. . . . He taught me on the business side. If he says one word, I understand how he thinks.”

Like her billionaire brother, Yingluck is skilled at connecting with Thais at the opposite end of the economic and social scale. She promises credit cards for farmers, debt relief and better health care. “Just because you have money, it doesn’t mean you don’t understand” poor people, she said. She also appeals to business, promising lower corporate taxes and a high-speed rail network.

Kraisak acknowledged that Yingluck was running a good campaign and had made things “very difficult” for his Democrat Party’s electoral chances. Her brother, he added, “is relentless.”