Prime Minister of Thailand largest political party in the lower house or the leader of the largest coalition of parties. In accordance with the constitution, the prime minister can only be appointed twice and is therefore limited to a maximum of two consecutive terms. The post of Prime Minister is currently held by Retired General Prayut Chan-o-cha, since the coup d'état on 22 May 2014. The office of the "President of the People's Committee" (), later changed to "Prime Minister of Siam" (), was first created in the Temporary Constitution of 1932. The office was modeled after the Prime Minister of the United Kingdom,
Acting prime minister is on vacation, or is in ill health. In the early 20th century, when travel by ship was still the norm, it was not uncommon for there to be an acting Prime Minister for months on end. The deputy Prime Minister is usually designated as the acting Prime Minister, although another senior member of the government may fill the role if both the Prime Minister and deputy Prime Minister are unavailable. An acting Prime Minister is required quite frequently – for instance, between 3 December 2007 and 23 February 2009 (during Kevin Rudd's first term), Julia Gillard acted as Prime