During her career teaching at the Communist Party’s top academy, Cai Xia cheered on signs that China’s leaders might ease their political grip, making her an uncommonly prominent voice for democratic change near the heart of the party.

Now Cai has turned her back on such hopes, and the party has turned against her. She has become the latest intellectual punished for challenging the hard-line policies of the current leader, Xi Jinping.

The Central Party School in Beijing, where Cai taught for 15 years until 2012, announced Monday that she had been expelled from the Communist Party after she denounced both the party and Xi in recent speeches and essays.