Chinese micro-bloggers and overseas websites have come up with all kinds of creative speculation as to why President-in-waiting Xi has gone unseen for more than a week. (Li Tao/AP)

Nearly two weeks, and still no sign of Xi Jinping.

China’s president-in-waiting has yet to resurface after cancelling appointments with foreign leaders and disappearing from public view. But late this week he wasmentioned in state-run media, which said he gave his condolences to the family of a long-time Communist Party official who died last week.

The reference to Xi — the first since Sept. 5 — appeared online in the state-run China News wire service on Wednesday, and it was repeated in several additional state-run outlets Thursday morning. Reuters on Friday reported that Xi was recovering from a bad back and cited three sources “close to the Chinese leadership” who said he could make a public appearance as early as Saturday.

The state media reports on Thursday listed Xi as one of several top leaders, including current President Hu Jintao, who passed along condolences after the death of a retired Guangxi region official named Huang Rong.

Huang died Sept. 6, one day after Xi’s first cancelled meeting, with visiting U.S. Secretary of State Hillary Rodham Clinton.

Xi hasn’t been seen in public since Sept. 1, and his disappearance has spawned endless speculation, just weeks before a sensitive once-in-a-decade leadership transition where he is supposed to take over the country’s reins.

Rumors about his absence continued Thursday, with a host of fresh news reports and unnamed officials supporting conflicting theories: a back problem, heart attack, swimming injury, car crash, a studious desire to seclude himself to adequately prepare for the coming party meeting.

The heart attack theory is favored by some experts because it’s severe enough to prevent Xi from doing a photo-op or public appearance but not so serious that it would put his ascension to China’s top post in question.

“It seems the most likely to me because the activity level of China’s other leaders seems to be quite normal the past few days. They’re all making their appearances, giving their speeches,” said Bonnie Glaser, a China expert at the Center for Strategic and International Studies. “I don’t know if they’d be doing that if something life-threatening had happened and they were facing a question of succession.”

One man — who, like Xi, is part of the group of children of revolutionary leaders, commonly called China’s “princelings” — said Xi’s mother told a concerned visiting princeling that her son was not feeling well but had not suffered anything serious.

The man spoke on condition of anonymity because of the party’s current crackdown on discussion of Xi. Search terms such as Xi’s name, references to his back and even his initials have been blocked on China’s popular Twitter-like microblogs.

Domestic politics could be thrown into turmoil if succession truly becomes an issue.

Because of the difficult balancing of opposing party factions that goes into picking China’s leaders, the top post is often negotiated years in advance in secret. And unlike countries such as the United States, which have detailed succession plans from the president down to the various cabinet secretaries, there is no clear plan for who replaces a leader who dies or becomes incapacitated — especially in rare moments of transition like this.

“The party doesn’t have a mechanism to handle such kind of succession crisis properly,” said Li Datong, a former editor of the state-run China Youth Daily and now a political analyst.

The era of total-control leaders like Mao Zedong or Deng Xiaoping, in which one official could decide the direction of the entire country, has given way to a period of consensus rule of a small council of party elites, each with their own power base.

“In some ways, it matters much less than in the past who the next president is,” Li said.

Even so, the health of that small group of leaders is shrouded in extreme secrecy, a practice rooted in history.

When then-Premier premier Li Peng disappeared for weeks in the 1990s, officials said he had a cold –an excuse later confirmed to be a cover-up for a heart attack.

When rumors swirled last year that former top leader Jiang Zemin had died, authorities shot them down with an official statement through the government-run Xinhua News Agency.

“The longer they delay on providing an explanation or arranging a Xi appearance, the more damage they are doing to their own position. It adds to the political problems they’re already dealing with,” said Kenneth Lieberthal, a long-time China analyst at the Brookings Institution. “For now, the only thing we know for sure is that we don’t know anything. There’s no hard evidence and no way to tell which rumor is true.”

Zhang Jie contributed to this report.