Why the Prime Minister cannot be a President: Comparing Institutional Imperatives in Britain and America

The notion of presidentialisation, applied to the British Prime Minister, usually focuses more on the personal style of the of the officeholder, less on the institutional substance of the office itself. The Prime Minister is the product of the British parliamentary system, and this system—and the institutional structures it imposes—provides for and circumscribes his or her powers. Comparing Britain with the US demonstrates that in executive-legislative terms a British Prime Minister is more commanding than any US President, while in intraexecutive terms the President is more powerful. The presidentialisation notion fails to acknowledge that its legislative purchase makes the British parliamentary executive more authoritative than its US presidential counterpart. Should, as is often but not always the case, a Prime Minister be able to lead his or her executive, determine its key decisions, shape its agenda and guide the work of its ministers, he or she will be a more influential actor than the President. Systemic differences distinguish Prime Ministers from Presidents. Britain does not have a presidential system, so it cannot have a presidential chief executive.