Vietnam may not have the polarizing elections that divide many democratic nations, but the ouster of a second president in just over a year shows that closed-door power struggles inside the one-party state can be just as brutal.

President Vo Van Thuong, 53, had been a rising star in the Communist Party, an ally and potential successor to ailing 79-year-old party chief Nguyen Phu Trong. Thuong’s resignation on Wednesday — a party statement vaguely said he "violated regulations on what party members cannot do” — instead leaves a leadership vacuum in what has been one of Asia’s fastest-growing economies.

"It’s another political earthquake in Vietnam,” said Nguyen Khac Giang, a visiting fellow at Singapore’s ISEAS-Yusof Ishak Institute. "It’s not really a good sign for a country often boasted for having very strong political stability.”