HONG KONG — With China’s propaganda apparatus in overdrive as the Communist Party demolishes the reputation of one of its former stars, a few defiant and angry fans are sticking to their guns.

“We support the Chongqing Model and Bo Xilai,” declared a call to arms posted on the Web site of the Progress Society, a pugnacious “new left” fraternity that trumpets the ousted Chongqing Party boss as a hero. Its logo features a panda wearing a Mao cap and clutching a rifle in front of a Chinese flag.

Bo, who until just a few weeks ago had a shot at joining the supremely powerful nine-member Politburo Standing Committee, has now been stripped of all his posts and is under investigation for “serious violations of discipline” while his wife is in detention on suspicion of murdering a British business consultant.

China’s new left is a disparate, volatile force, united only by a vague sense that the country has taken a wrong turn by pursuing economic growth above all else. Members range from nationalist firebrands and prominent intellectuals to discontented princelings, such as Hu Yingmu, the elderly daughter of Mao Zedong’s longtime secretary.

“The real concern in Beijing is that the links here are unpredictable, difficult to gauge and largely underground,” said Patricia Thornton, a scholar of Chinese politics at the University of Oxford. The jittery mood in Beijing, heightened by unfounded recent rumors of a coup, gives the new left “more heft than it would otherwise have in normal times and contributes greatly to sense of uncertainty as the next transition looms” at the Party’s 18th Congress later this year.

Most of Bo’s previously outspoken supporters have now fallen silent in the face of a steamroller of official denunciation. But hit-and-run polemic strikes are being made on Web sites and Twitter-like micro-blogs.

The Progress Society site, which is officially blocked in China but is still accessible to legions of Internet users who know how to skirt the “Great Firewall,” froths with bile and often personal attacks on Party leaders, particularly Prime Minister Wen Jiabao, a relative liberal whom Bo’s supporters blame for his downfall.

“Fake communists have seized power in new China,” read a message flashing across the top of the home page Friday.

Who stands behind the site, first registered to an address in the central Chinese city of Zhengzhou in 2010, is not known. There have been rumors of a connection to hard-line nationalist elements in the People’s Liberation Army. But it could also be tied to overseas activists intent on stirring tumult as the Party struggles to contain the biggest political crisis since the 1989 Tiananmen Square massacre.

Bo had staked his political career and also won many fans by promoting a so-called Chongqing model: a mix of retro rhetoric and rituals from the Mao era, a ferocious campaign against alleged gangsters (often just rich people, say critics) and an emphasis on narrowing a widening gap in China between the wealthy and the poor.