Momentum is a British left-wing political organisation. It has been described as a grassroots movement supportive of the Labour Party. Since January 2017, all Momentum members must also be or become members of the Labour Party. The organisation was reported to have 40,000 members in 2019. It has close links with The World Transformed., It was founded in 2015 by Jon Lansman, Adam Klug, Emma Rees and James Schneider, following the successful campaign for Jeremy Corbyn to become the Leader of the Labour Party. The current officers of Momentum Campaign Ltd are: Lansman, Sam Tarry MP, Mossley Hill Councillor Elizabeth Hayden, solicitor Anthony Kearns, and Professor Cecile Wright of the University of Nottingham. The organisation has polarised Labour politicians and journalists since its inception. Some have compared it to the Militant tendency within the Labour party; however, others have praised its grassroots engagement as well as its effective and virally spread but low budget information videos, such as those used in the 2017 general election campaign.