The prime minister of the United Kingdom exercises functions in both the executive and the legislature, as the UK has a fusion of powers.
Executive powers of the prime minister include obtaining at any time the appointment or dismissal of all other Government ministers, exercising the royal prerogative, setting the Government's policy agenda and priorities, and deploying the British Armed Forces overseas. In the legislature, the prime minister normally (but not necessarily) leads the largest party in the House of Commons, and therefore can normally gain Parliamentary support for their desired legislation. Most of the time the prime minister can control what is debated in the House of Commons, and when, as Government business has precedence (that is, priority) on every day it sits. General Elections are called at a time of the prime minister's choosing, with a legal maximum of five years between Elections. The prime minister, and other ministers appointed by the prime minister, make many of the most senior Crown appointments. The prime minister also has some power over their own party, in their role of party leader.