As the leader of one of the largest pro-democracy parties in Hong Kong’s legislature, Alvin Yeung could make history if the city’s opposition wins an unprecedented majority in September elections. Or he could find himself disqualified before the campaign even starts.

The 39-year-old lawyer is among several prospective candidates accused by Chinese authorities of behavior that opposition politicians fear could be used to bar them from running or expel them after the vote. After rejecting a half dozen "localist” candidates for seeking independence from China four years ago, the government and its supporters have criticized activists by name for a growing range of actions that could run afoul of the new national security legislation and other laws.

On Friday, for instance, China’s top agency for Hong Kong accused Yeung of "glorifying illegal behavior” in a statement denouncing several other high-profile politicians. At the same time, he was featured on decks of novelty playing cards handed out in the city showing pictures of prominent opposition figures superimposed against prison bars and listing their "crimes.”