Sunia was the administrative officer for the Samoan affairs-liaison functions for the Governor of American Samoa, and served as a translator and interpreter and an election commissioner. He was the founder of the Samoan News newspaper and director of tourism for the Government of American Samoa, a territorial Senator and president and chairman of the American Samoan Development Corporation.
He was elected as a Democrat to the United States House of Representatives, and served from January 3, 1981 until his resignation on September 6, 1988. He is a resident of Pago Pago.