After leaving office, Mahathir became a strident critic of his hand-picked successor Abdullah Ahmad Badawi and later Najib Razak. In 2016, Mahathir quit UMNO-BN in light of its support for Prime Minister Najib's actions despite the 1Malaysia Development Berhad scandal. Later that year, the Malaysian United Indigenous Party was officially registered as a political party, with Mahathir as chairman. In 2018, Mahathir was announced as the Pakatan Harapan coalition candidate for prime minister for the 2018 general election, in a plan to pardon Anwar Ibrahim and hand a role to him if the campaign was successful. Following a decisive victory for Pakatan Harapan in the 2018 election, Mahathir was sworn in as prime minister. He was the first prime minister not to represent the Barisan Nasional (BN) coalition (or its predecessor, the Alliance Party) and also the first to serve from two different parties and on non-consecutive terms. At the time of his resignation, during the 2020 Malaysian political crisis in February 2020, he was the oldest currently-serving state leader.