The Prime Minister of the United States of Europe was the head of government for the United States of Europe. The office was established in 1633, not long after the Confederated Principalities of Europe collapsed and was replaced by the USE. Both the existence of the office and its powers were set out in the Constitution of the United States of Europe. As the office was patterned rather closely on the up-time office of the Prime Minister of the United Kingdom, the powers of the USE's government rested primarily with the PM, rather than with the Emperor of the United States of Europe, the head of state of the USE.