He was originally seen as an "outsider" in the leadership race. This means that, though he was a member of the Labour Party, he was not someone people expected to be leader. Bookmakers had his odds of winning at 200-to-1. However, following a series of televised and radio debates with the other three candidates – Andy Burnham, Yvette Cooper and Liz Kendall – Corbyn went on to gain the support of six of the fourteen trade unions affiliated with the Labour Party. This included the UK's two largest trade unions, Unite and UNISON. He received the highest number of supporting nominations from Constituency Labour Parties, winning over 100 by the end of July.