Throughout the Middle Ages, Denmark utilized what is known as an elective monarchy to crown its next ruler. This form of government contrasts with the common form of hereditary monarchy where the office of king is passed down to the oldest son. In an elective monarchy, the parliament, which consisted of Lords, elects the country's next ruler. While Prince Hamlet was in Germany attending the University of Wittenberg, Claudius usurps power after he murders his brother, King Hamlet. It is plausible that Claudius stepped in to receive the crown after his brother died by using the Queen's influence to win the necessary parliamentary votes needed to become king. In Act IV, Scene 2, Hamlet alludes to how Claudius became king by saying,
He that hath killed my king and whored my mother, Popped in between th' election and my hopes (lines 69-70).
Hamlet laments how Claudius essentially stole the thrown and mentioned that he intervened in the election to become king. One can infer that if Claudius was clever enough to seduce Gertrude and murder King Hamlet, he more than likely used Gertrude to influence the Lords to elect him king of Denmark while Prince Hamlet was out of the country.