The Left Caucus was an Ontario-based left-wing pressure group within the New Democratic Party of Canada and the Ontario New Democratic Party from the late 1970s to early 1990s.
The Caucus was formed several years after the demise of The Waffle, an earlier left-wing faction which had been forced to leave the NDP in the mid-1970s.
It was formed by 150 to 200 members in the lead up to the NDP's 1979 federal convention to which it proposed a series of radical resolutions promoting greater public ownership of the economy and other socialist and left-wing measures. John Rodriguez, Member of Parliament for Nickel Belt, was the leading spokesperson for the caucus. Another notable founding member of the Left Caucus was Ontario NDP MPP and future provincial finance minister Floyd Laughren.
Rodriguez said the caucus different from the Waffle in that its ultra-left elements were a minor part and as it was willing to abide by the final resolutions of the convention, whether it agrees with them or not. However, Rodriguez warned that the Left Caucus would be outspoken if resolutions it favours passed the convention but were ignored by the party's leadership.
The only one of the caucus' resolutions to be approved by the 1979 convention, however, was one protesting the jail sentence handed to Jean-Claude Parrot, president of the Canadian Union of Postal Workers for leading a wildcat strike.
In 1981, the Left Caucus opposed Bob Rae's successful candidacy for the leadership of the Ontario NDP backing MPP Richard Johnston instead.
Prior to the 1983 federal convention, the Left Caucus again pushed for the party to adopt an economic policy focussed on nationalization of industry and issued a document decrying "the half-measures of a mixed economy" and calling for "a socialist industrial strategy based on public sector ownership of the decisive sectors of the economy." The caucus unsuccessfully opposed the adoption of a new "statement of principles" by the NDP in 1983 which watered down the party's commitment to socialism and the planned economy.