Labour Party (UK)
In 2015, dark horse candidate Jeremy Corbyn announced his candidacy for the leadership of the Labour Party. At the beginning, he was thought of as a socialist fringe candidate, but he later became the lead candidate in polls and got the support of the majority of trade unions affiliated to the Labour Party, along with those of three non-affiliated unions. On 12 September 2015, he was elected Leader of the Labour Party, with a majority vote of 59.5% in the first round of the ballot.