But it is already near impossible to hold a private conversation with anyone in the Chinese capital who takes an interest in politics without talk turning to Mr. Guo and his unverified insider tales of elite corruption and power plays. People here have followed each unveiling of Mr. Guo’s often long-winded allegations by creeping around China’s barricade of internet censorship.

“I don’t think the party has ever had a big businessman so boldly challenge it like this,” said Bao Tong, a former senior aide to Zhao Ziyang, a former party leader who was toppled from power during the 1989 protests. “How to respond is a dilemma.”

Mr. Guo, who also goes by the name Miles Kwok, has delighted in doling out his allegations on a lively Twitter feed as well as in hourslong talks and interviews broadcast, sometimes live, on YouTube and Mingjing, a Chinese news website based in the United States. All those sites are blocked in China.

During a broadcast in mid-June, which went on for more than four hours, Mr. Guo seemed to enjoy teasing the interviewer.

“I don’t get how you’re just sitting there. Are you made from flesh and blood?” Mr. Guo said as he laid out pictures and diagrams that he said proved his claims. “Such huge news. Why don’t you take off your clothes and get excited?”