He has been president of the Democratic Party since 2010,[1] three time presidential candidate and served as the Local Council 5 chairman for Gulu District.

[6] From 1992 until 1994, Mao worked as an associate attorney in the offices of Kabugo and Company Advocates, a Kampala-based law firm.

[7] Mao is chairman of the East African chapter of the Parliamentary Network on the World Bank and member of its secretariat.

He was instrumental in trying to bridge the gap between the Lord's Resistance Army rebels and the Ugandan government by lobbying for the passage of a general amnesty law aimed at bringing a peaceful resolution to armed conflict in northern Uganda.

Mao and Inter Party Coalition presidential candidates Kizza Besigye and Olara Otunnu, among others, protested the election results in spite of its early approval by international observers and the United States as largely free and fair.

[11] On 21 November 2020, Mao, along with fellow opposition presidential candidates Bobi Wine, Henry Tumukunde, Mugisha Muntu, and Patrick Amuriat Oboi, agreed to form an alliance.

[12] On 20 July 2022, Mao was appointed Minister of Justice and Constitutional Affairs by president Museveni in a move that sparked off a debate about his allegiance to the opposition.