New Democratic Party leadership elections, more commonly known as leadership conventions, are the process by which the Canadian New Democratic Party elects its leader. Before 2003, when a modified one member, one vote (OMOV) system was adopted, every biennial New Democratic Party convention, since 1961, was a leadership convention. However, in practice, contested elections were held only when there was a declared leadership race. The earliest example of an incumbent leader being challenged from the convention floor happened in 1973 when Douglas Campbell unsuccessfully opposed David Lewis' leadership. In 2001, Socialist Caucus member Marcel Hatch challenged Alexa McDonough from the floor of the convention; however, McDonough easily retained the leadership in the resulting vote.