Mainstream (political organisation)

Mainstream Labour or simply Mainstream is a British centre-left political network associated with the British Labour Party, co-founded by Open Labour and Compass in September 2025 to reverse what it sees as Labour's "clear drift to the right" under Keir Starmer to prevent the rise of right-wing populism in the UK. Ideologically described as sitting on the soft left of the Labour Party, Mainstream describes itself as the home of Labour's "radical realists" and promotes a democratic socialist platform which includes taxing wealth, introducing democratic reforms and placing key utilities into public ownership.

According to its founders, Mainstream is intended to serve as a broad-church for Labour's progressive left, including both members on the Labour left and centrists associated with New Labour, rather than a political faction or caucus. Its membership is formed from a broad alliance of Labour politicians on the Labour left and soft left, as well as the more progressive elements of New Labour.