A former vice president in Zimbabwe announced plans Tuesday to run in elections scheduled for 2018 against President Robert Mugabe.

Joice Mujuru said her new political party, Zimbabwe People First, is willing to form a coalition with other opposition groups.

Mujuru was once a close ally of Mugabe, who celebrated his 92nd birthday last month as his ZANU-PF party is splitting into factions ahead of an expected succession battle.

Mujuru was Zimbabwe's first female vice president but ran afoul of Mugabe's increasingly politically active wife Grace, who campaigned for Mujuru's ouster in 2014.

Mugabe has been endorsed as the ZANU-PF candidate for the 2018 elections.