Prime minister leader, the incoming leader will usually be referred as "prime minister-in-waiting". An example or this situation was in 2016 in the United Kingdom when Theresa May was elected leader of the Conservative Party while David Cameron was still prime minister. Ukraine's constitution (1996) lists the powers, functions and duties of the Prime Minister of Ukraine. Most prime ministers in parliamentary systems are not appointed for a specific term in office and in effect may remain in power through a number of elections and parliaments. For example, Margaret Thatcher was only ever appointed prime minister on "one" occasion, in 1979. She
Prime minister Bahrain's prime minister, Sheikh Khalifah bin Sulman Al Khalifah has been in the post since 1970, making him the longest serving non-elected prime minister. The post of prime minister may be encountered both in constitutional monarchies (such as Belgium, Denmark, Japan, Luxembourg, the Netherlands, Norway, Malaysia, Morocco, Spain, Sweden, Thailand, Canada, Australia, New Zealand, and the United Kingdom), and in parliamentary republics in which the head of state is an elected official (such as Finland, the Czech Republic, France, Greece, Hungary, India, Indonesia (1945-1959), Ireland, Pakistan, Portugal, Montenegro, Croatia, Bulgaria, Romania, Serbia and Turkey (1923-2018)). See also "First Minister", "Premier",