he was appointed Minister of Post and Telecommunications in the cabinet of President Chandrika Bandaranaike Kumaratunga in 1994. He also served as the Minister of Urban Development, Construction and Public Utilities in the same Cabinet after a reshuffle and was later given the Deputy Minister of Finance portfolio. Following the election defeat of his party in 2001, he was made the Chief Opposition Whip and the Treasurer of the Sri Lanka Freedom Party. In 2004 he became the Minister of Ports, Aviation and Media in the new cabinet of President Chandrika Bandaranaike Kumaratunga. In June 2005, after conflicts with Kumaratunga, he dropped the Media Ministry, but remained Cabinet Minister of Ports and Aviation. He became the campaign manager for Presidential candidate and Prime Minister Mahinda Rajapakse. When Rajapakse won and took office in November 2005, he surprised many by appointing Samaraweera to the additional post of Foreign Minister instead of Prime Minister; Samaraweera maintained his other posts. In late January 2007, Samaraweera was replaced as Foreign Minister, but remained as Minister of Ports and Aviation. On 9 February 2007, he was sacked from the cabinet together with ministers Anura Bandaranaike and Sripathi Sooriyarachchi after falling out with the then president Mahinda Rajapaksa. He then went on to create a new political party, the SLFP (Mahajana) wing. Mangala later became a vocal critic of Rajapaksa family and Rajapaksa government after being ousted by Mahinda Rajapaksa from his cabinet. In October 2013, the Matara Magistrate's Court issued a Court order to arrest him and 10 others for their alleged involvement in obstructing a peaceful protest march in Matara by UNP activists, to oust its leader Ranil Wickramasinghe. On 12 January 2015, Samaraweera was again appointed Minister of Foreign Affairs under newly elected President Maithripala Sirisena. During the 2015 Presidential election, he played a pivotal role as a joint spokesperson of the opposition coalition candidate Maithripala Sirisena. After the 2019 Presidential election, Samaraweera joined the newly formed Samagi Jana Balawegaya which was launched in 2020 and led by opposition leader Sajith Premadasa. Mangala was reported to have played a major role in the break up of the United National Party and also led the formation of Samagi Jana Balavegaya. He resigned from the position of Finance minister as of 17 November 2019 only hours prior to release of the general election results. In June 2020, he announced that he would not contest the