House of Cards (1990)

Francis Urquhart is the Chief Whip of the Conservative Party. When Margaret Thatcher resigns as leader, he remains neutral and, after a general election in which the Conservatives are returned with a reduced majority, he fully expects the new Prime Minister, Henry Collingridge, to give him his just reward: a senior Cabinet post. When he's informed that he is to stay in his current position, he devises a plot to unseat Collingridge and ensure his own election as party leader which would make him Prime Minister.