Omar helped found and joined the
Malayan Chinese Association (MCA) in 1949. As a prominent Chinese leader, Ong was selected by the
British High Commissioner as a member of the then fully appointed
Selangor State Council and
Federal Legislative Council. In 1952, he and Yahya Abdul Razak mooted the idea of an alliance between MCA and the
United Malays National Organisation (UMNO) for the
Kuala Lumpur Municipal Council elections. This was the precursor to the formal
Alliance Party. He contested and won a seat in that election, and was chosen as leader of the Alliance Party in the Municipal Council. Omar went on to become MCA vice-president and the
member of parliament for
Hulu Selangor. In 1955, the Alliance Party won the
first ever elections to the Federal Legislative Council under the leadership of
Tunku Abdul Rahman. Omar was appointed Minister for Post and Telecoms in the Tunku's first Cabinet. Following the overwhelming support shown for the Alliance Party during the elections and the forming of the government, the Tunku led the Merdeka Delegation to
London which successfully negotiated independence from the British. Omar joined the Tunku on his second trip to London in April 1957 to finalise the newly drafted
Constitution of Malaya.
Independence and the formation of Malaysia On 31 August 1957, Omar was appointed to the
first Rahman cabinet of the newly independent
Federation of Malaya, holding the Labour and Social Welfare portfolio. In 1959, he became health minister. During negotiations to unite Malaya,
Singapore,
Sarawak and
British North Borneo (later known as
Sabah), Ong was ambassador to the
United Nations as Malaya focused on diplomacy amid regional tensions with
Indonesia (
Konfrontasi). Following the proclamation of the Federation of
Malaysia, Ong continued to serve in the Cabinet as minister without portfolio until 1973. He served concurrently as High Commissioner to Canada in 1966 and as ambassador to Brazil from 1967 to 1972. In 1973, he was elected
President of the Dewan Negara and served until 1980. ==Personal life==