A group of Chinese leftists has signed a petition urging parliament not to expel disgraced leader Bo Xilai, saying he could be exposed to an unfair and politically motivated trial.

The letter, signed by hundreds of academics and former officials, was published on the far-left Red China website. It comes as China's largely ceremonial parliament is expected to remove Bo as a lawmaker, stripping him of legal immunity.

Once a rising star in Chinese politics, the divisive and charismatic Bo is thought to still command the respect of many left-leaning Chinese because of his calls for a Mao-era “red revival.”

Bo has already been expelled from the Communist Party as a result of a scandal that has seen his wife convicted of murder. Last month, state media said he will “face justice” for charges including abuse of power, taking bribes, and improper sexual relations.

But the petition, which is also circulating on other sites, condemned the expulsion of Bo from the party, saying the facts of the case against him are “unclear.” It said he should have a chance “to defend himself in accordance with the law.”

Bo has not been seen or heard from since February, when his ex-police chief fled to the U.S. consulate in Chengdu with details of the murder of British businessman Neil Heywood. His wife, Gu Kailai, was convicted of murdering Heywood over a business dispute and given a suspended death sentence.

Before his downfall, Bo had been considered a favorite to be named to the powerful Politburo Standing Committee, China's highest decision making body, during a leadership transition set to begin in two weeks.

Observers say negotiations among senior Communist Party officials regarding Bo's fate reflect a deeper rift within the party. Some say it has become a bargaining chip in the leadership succession.