With his wife Gu Kailai and his top aide sentenced, and a political transition pending, Bo Xilai remains hidden. (Andy Wong/AP)

His wife is in jail on a murder conviction with a suspended death sentence. His former right-hand man was just sentenced to 15 years in prison for covering up the crime and then trying to defect to the United States.

Somewhere, Bo Xilai awaits his fate.

A popular and charismatic Communist Party “princeling” — considered a contender for a top spot in a revamped Politburo until the murder scandal erupted last year — Bo has not been seen publicly since he was fired in March as party chief for the sprawling southwestern city of Chongqing.

How to handle Bo without upsetting his hard-core supporters seems to be the dilemma facing China’s leaders as they try to resolve the case before a planned leadership transition later this year.

The Communist Party’s 18th Party Congress is set to inaugurate a new generation of leaders, led by Xi Jinping and an almost entirely new Politburo Standing Committee. But no date has been set for the conclave, leading many here to speculate that the top leaders have not resolved some thorny issues, including the question of what punishment, if any, will be handed to Bo.

“If they don’t handle this problem well, it might threaten the stability of the party,” said Tie Liu, a journalist who spent 23 years in a labor camp during Mao Zedong’s “anti-rightist” campaign launched against intellectuals in 1957.

He said he believed the party would opt for a mild administrative punishment, perhaps penalizing Bo for failing to properly supervise his family members and subordinates, and would announce it after the leadership transition. Others agreed with that analysis.

“They just don’t want him to return. . . . He’ll no longer be able to hold any official position,” said the editor of a Communist Party newspaper in Beijing who spoke on the condition of anonymity in order to speak more freely. “If he’s expelled, the party would split, because many leftists in the party still support him.”

Bo, the son of Mao-era revolutionary hero Bo Yibo, was the antithesis of the typical Chinese politician: charismatic where most are bland, outspoken when others are reticent, open to the media when most eschew publicity, and bold in a system that prizes uniformity and consensus.

Bo is also something else highly unusual in China’s staid communist bureaucracy. He is popular.

In Chongqing, the isolated city where he served as party chief from late 2007 until his ouster, Bo is well-regarded for clearing out the organized gangsters who held sway, attracting foreign investment and providing low-income housing and school lunches to the poor.

Among China’s “new left” intellectuals, disgruntled over China’s growing income disparity and nostalgic for Mao-era class warfare, Bo was revered as something of a hero. His “Chongqing model,” as it was called, was held up as an alternative to China’s modern, get-rich-quick brand of capitalism, in which a very few have become very, very wealthy. His advocacy of “red culture” — singing revolutionary songs, playing patriotic broadcasts on the local television station — also endeared him to the new leftists.

“Chinese leftists find that many of Bo’s policies are similar to their ideas,” said Sima Nan, a blogger and one of the best known of the new left thinkers. “So they regard Bo Xilai as their spirit leader.”

Bo’s only known communication with his family since his ouster was an emotional letter sent in April to his mother-in-law, Fan Chengxiu, written with a traditional Chinese brush. Bo said he hoped to quietly read books while waiting for his case to be resolved, according to a family associate who saw the letter.

Bo described his wife, Gu Kailai, as the most important person in his life, followed by Fan, who became like a mother to him because his mother died during the Cultural Revolution, the associate said.

Gu was convicted in August of poisoning a British businessman, Neil Heywood, whom she thought threatened their son after a business dispute. Bo’s onetime top aide and police chief, Wang Lijun, was tried for helping Gu cover up the crime and then taking the evidence to the U.S. Consulate in Chengdu in February when he feared for his life. Wang on Monday was sentenced to 15 years in prison, a relatively light sentence because Wang cooperated in implicating Gu. Wang’s attorney said he would not appeal.

But the separate trials of Gu, Wang and four other police officers charged in the coverup left unanswered the crucial question of what Bo knew about the murder and when he knew it. Bo in April was stripped of his positions in the Politburo and the Party Central Committee, but he has not been charged with any crime.

He is thought to have been moved several times among government residences in Hebei province, Inner Mongolia and the outer suburbs of Beijing. Those reports could not be independently confirmed.

The family associate, who saw the letter Bo wrote to his mother-in-law but refused to be identified by name in discussing it, said Bo reiterated his commitment to Communist Party ideals.

“Bo Xilai really believes in Chairman Mao,” the family intimate said. “He was rooted in Mao Zedong’s thoughts, which can be found everywhere in his values, life goals and his pursuits.”

Zhang Jie in Beijing contributed to this report.