BEIJING—Supporters of ousted political leader Bo Xilai are turning up the note of political discord in China with increasingly loud criticism that the policies of current Communist Party leaders are widening inequality and breeding social unrest.

The movement, known as the new left, remains relatively small and obscure, and is unlikely to have a major impact on the coming shuffle of party leadership positions. But criticism from Communist hard-liners in the era of online social media places China's leaders in a tricky position as a debate over the direction of the party and China's economic model is quickly spreading from universities and closed-door sessions into public view.

The new left—a loose collection of academics, lower-ranking government officials, writers and overseas activists—advocates a stronger hand for the state in economic planning as well as a return to the values put forth by the late Chairman Mao Zedong. The new left argues that China's economic reforms over more than 30 years have led to wide income disparity, and the movement has criticized the takedown of Mr. Bo, once its most visible leader.

Dealing with the new left requires some balancing for the party. Unlike the political activists who often oppose the party on democratic or human-rights grounds, the new leftists act as defenders of the vision Mao once laid out for China: Rejecting them outright would risk exposing party leaders to sensitive questions around the very foundation the party is built on.

Mr. Bo's takedown indicates consensus among Chinese leaders to push ahead with economic liberalization despite growing social problems, said Minqi Li, an economics professor at the University of Utah, who is aligned with new leftists in calling for more-egalitarian wealth distribution in China.