Treasury (office in commission) or more rarely Chancellor of the Exchequer (the last of whom was Balfour in 1905). In such systems unwritten (and unenforceable) constitutional conventions often outline the order in which people are asked to form a government. If the prime minister resigns after a general election, the monarch usually asks the leader of the opposition to form a government. Where however a resignation occurs during a parliament session (unless the government has itself collapsed) the monarch will ask another member of the government to form a government. While previously the monarch had some leeway in whom to ask, all British political parties now elect their leaders (until 1965 the Conservatives chose their leader by informal consultation). The last time the monarch had a choice over the appointment occurred in 1963 when the Earl of Home was asked to become Prime Minister ahead of Rab Butler. During the period between the time it is clear that the incumbent government has been defeated at a general election, and the actual swearing-in of the new prime minister by the monarch, governor-general, or president, that person is referred to as the "prime minister-elect" or "prime minister-designate". Neither term is strictly correct from a constitutional point of view, but they have wide acceptance. In a situation in which a ruling party elects or appoints a new 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. Russia's constitution (1993) lists the powers, functions and duties of the prime minister of Russia. Ukraine's constitution (1996) lists the powers, functions and duties of the prime minister of Ukraine. Lists of prime ministers The following table groups the list of past and present prime ministers and details information available in those lists. See also List of current prime ministers by date of assumption of office Chancellor Chief Minister Governor-General Head of government Head of state Monarch President Prime ministerial government Lists List of current heads of state and government List of democracy and election-related topics Notes References Further reading Andrew Blick & George Jones, Premiership: The Development, Nature and Power of the Office of the British Prime Minister (Exeter: Imprint Academic, 2010), . Michael Foley, The British Presidency (Manchester University Press, Manchester, 2000) Peter Hennessy,