Over the past week, Beijing has been baked by searing heat and shrouded in a heavy blanket of smog, reducing visibility and irritating millions of people. The smog-filled skyline, if it persists, does not augur well for the elaborate celebrations planned for Tiananmen Square on August 8 to mark the one-year countdown to the Beijing Olympics. The smoggy and muggy weather could also serve as a metaphor for the intensity and uncertainty of the behind-the-scenes power struggle being waged among the capital city's political circles. In the mainland's pervasively secretive politics, nothing is more closely guarded than the leadership reshuffle to be discussed and approved at the Communist Party Congress, in this case the 17th congress scheduled for October. With the state media muzzled and public debate prohibited, overseas analysts have little choice but to resort to reading tea leaves, sifting through incessant waves of speculation and official statements. An example is the mainland leadership's decision last Thursday to strip former Shanghai party secretary Chen Liangyu of his party membership and all his official posts, and to turn him over to prosecutors following a 10-month corruption investigation. The announcement has put to rest speculation that President Hu Jintao was unable to have Chen swiftly prosecuted because of opposition from former president Jiang Zemin , the head of the so-called Shanghai Gang, of which Chen is a prominent member. But it has created a new wave of speculation about a possible power struggle between Mr Hu and Mr Jiang. According to the announcement, Chen's alleged crimes - which included taking bribes, keeping mistresses and abusing power to help his associates and family members - started nearly 20 years ago, when he was the head of Shanghai's Huangpu district. The unspoken implication cannot be clearer: Chen had long been protected by his mentor, Mr Jiang, who became the mayor of Shanghai in 1985. Otherwise, the announcement could have simply focused on Chen's recent crimes, including the biggest - misappropriating over 3 billion yuan from Shanghai's pension fund. By taking a dig at Mr Jiang, however, the announcement has also provided evidence that the anti-corruption campaign against Chen was politically motivated, and pokes fun, however unwittingly, at the party's claim that toppling Chen was a sign of its determination to root out corruption. From reading these tea leaves, at least, one can infer that Mr Hu has clearly won this round and strengthened his influence in the party. But the die is far from cast. As the congress draws nearer, the overseas media are filled with speculation on the candidates for the nine-member Politburo Standing Committee and the 20 or so members of the Politburo itself. Partly reflecting their own wishes, the overseas analysts are betting that the odds favour Mr Hu's allies and supporters. But the optimism might be misplaced. Contrary to widespread speculation that Mr Hu has dominated the reshuffle game, and that key appointments have already been largely decided, the word in Beijing's corridors of power is that the jockeying is intensifying to such a degree that consensus cannot be reached on key appointments, and the congress could be delayed from the first half of October to the latter half. The rumours that Mr Jiang has little influence over the impending reshuffle are also incorrect. Many of his supporters still have a good shot at top leadership positions. One is Zhang Dejiang , the party secretary for Guangdong province. Soon after Mr Zhang was appointed to his current position in 2002, a concerted campaign to discredit him began in the Hong Kong media, purportedly started by Guangdong officials. This campaign blamed him for a series of riots in the province, including the infamous incident in Shantou in which police shot dead a number of unarmed protesting farmers. But as a savvy political operator, Mr Zhang has earned the trust of the mainland leadership by complying with the central government's directives, in contrast to Chen's rash challenges against them. Mr Zhang is also not as conservative as many analysts believe him to be. In the early days of student demonstrations and before the bloody Tiananmen crackdown in June 1989, Mr Zhang, then a deputy minister of civil affairs, was one of the few senior government officials to publicly express sympathy for the students. In 1990, he was appointed party chief of Yanbian in Jilin province . This was widely seen as a demotion. But he demonstrated his political resilience by climbing his way up the ranks to become the provincial party chief five years later. It will be little surprise if Mr Zhang is made a member of the Politburo Standing Committee and an executive vice-premier in October. If any big surprise comes from the congress, it is most likely to concern the premiership of Wen Jiabao . Last month, Japan's Kyodo news agency quoted unidentified sources as saying that Mr Wen felt that five years of running the country was enough, because of the heavy workload, but he would continue to serve on the Politburo Standing Committee. Beijing reacted swiftly to the report, when it would normally ignore such rumours. The Foreign Ministry spokesman quickly denied the report and summoned the Kyodo reporters for a tongue-lashing. This unusual denial could mean the report touched a raw nerve. Mr Wen has earned a reputation as the 'people's premier' for his down-to-earth manner and his affection for the poor and powerless. However, he faces increasing pressure to find ways to curb the soaring property market and rising inflation, as well as the worsening environmental degradation. He is also beset by intense rumours over the business activities of his family members, while many conservative party members are wary of his liberal ideas.