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
Historical rankings of Prime Ministers of the United Kingdom using a 0 to 10 scale, where 0 meant highly unsuccessful and 10 meant highly successful. Overall, MPs rated Margaret Thatcher as the most successful post-war Prime Minister, just ahead of Clement Attlee. With the exception of Edward Heath, who was judged more favourably by Labour MPs than by Conservatives, evaluations were split along party lines: Tory MPs tended to consider Conservative prime ministers to be more successful than did Labour MPs, and Labour MPs generally gave Labour prime ministers higher scores than did Conservative MPs. In October 2016 the University of Leeds, in conjunction with Woodnewton Associates, surveyed 82