Tang, initially believed to be Beijing's preferred choice to succeed Tsang, is another big target.
He admitted an extramarital affair, and then his popularity sank further following revelations of an illegally built 2,250-square foot (209-square meter) basement that reports said was outfitted with a Japanese spa, home theater, wine cellar and wine tasting room. In a city where most people live in tiny apartments and the government has been trying to crack down on illegal structures, it sparked outrage over double standards.
Polls show his approval rating has fallen to about 19 percent. But the heir to a textile fortune has the backing of tycoons including Li Ka-shing, the city's richest man.
Leung, the son of a police officer, is popular with the public. Polls show he has the support of more than 50 percent of the population. That's despite allegations that when he was a judge on a decade-old design competition for an arts center, one of the contestants was linked to his own property firm. Lawmakers have voted to investigate.
This year's mudslinging and muckraking have created a dilemma for China's communist leaders.
Tang's scandals are making them think twice about their initial support because they don't want him undermined by public doubt from the start, said Dixon Sing, an associate professor of political science at Hong Kong University of Science and Technology.
Leung, however, is making the tycoons apprehensive because he's seen as more willing to carry out large-scale social policy reforms that could undermine their business interests, Sing said.
For example, Leung wants to boost public housing supply in land-scarce Hong Kong, which would upset the billionaires who have built property development empires.
Beijing has delivered no clear public signals on which way it's now leaning. Vice President Xi Jinping, who's expected to be named China's next president later this year, gave no hint when he met the two candidates at a recent high-level meeting in Beijing.
As the March 25 selection date looms, Beijing faces a tough choice: choose one and risk upsetting the tycoons, choose the other and risk an explosion of public anger.
Henry Tang's campaign website: http://www.wearetomorrow.hk
Leung Chun-ying campaign website: http://www.cyleung2012.com/
Follow Kelvin Chan at twitter.com/chanman
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