NAIROBI, Kenya (AP) — Kenyan opposition leader Raila Odinga on Monday chose a former justice minister as his running mate in elections set for August, making her the first-ever female candidate on a major presidential ticket in the East African country.

Martha Karua, an attorney and seasoned politician, has a reputation for speaking her mind and could prove a popular choice among voters excited to see a woman among the country's top leaders.

Karua, who unsuccessfully ran for president in 2013, is nicknamed “the iron lady" for her reputation as a tough competitor and has railed against official corruption.

“I believe in my heart of hearts that if we can erode the power of corruption in our midst, we can finally cross the Rubicon to the promised land,” she said in a speech Monday.

Odinga's announcement came the day after his rival, Deputy President William Ruto, picked lawmaker Rigathi Gachagua as his running mate. Both running mates are ethnic Kikuyus — underscoring the importance of that voting bloc that encompasses a wide and ballot-rich part of central Kenya.

Odinga praised Karua as an “exceptional leader with high principles," adding that by choosing her he has demonstrated his confidence in the leadership of women.

Opinion polls show a tight race between Odinga and Ruto in the increasingly feisty fight to succeed President Uhuru Kenyatta.

Kenyatta, who has served two terms, fell out with his deputy at the start of his second term when Kenyatta and Odinga — who had lost the 2017 polls — shook hands in public in what was seen as a show of unity after divisive elections.

But the so-called handshake incident in 2018 rattled Ruto, who saw it as a betrayal. Ruto and Kenyatta have since been at loggerheads, sometimes attacking each other's records in public. Kenyatta is actively backing Odinga.

Voting, which is scheduled for Aug. 9, could yet again test Kenya's political stability in the event of a disputed outcome.

Kenyan elections often end in legal suits and a fiercely fought election in 2007 sparked ethnic violence in which more than 1,000 people were killed.

William Ruto

Top Kenyan presidential candidate picks female running mate