Maurice Spector, editor of the Communist Party newspaper The Worker, had been a Canadian delegate to the 1928 Comintern Congress in Moscow when he and American James Cannon inadvertently came across the suppressed platform of Trotsky's Left Opposition.
The Fieldite group, under Krehm's leadership in Canada, published Workers Voice and was, for a time, more active than the Trotskyists but faded away by the outbreak of World War II.
They reunited with the faction that had opposed CCF work, and formed the Socialist Workers League in 1939 with Earle Birney as the principal leader as Macdonald and Spector had both dropped out of the movement.
The group was relaunched in 1946 as the Revolutionary Workers Party (RWP), Canadian Section of the Fourth International, under the leadership of Ross Dowson.
The foundations of the party had been laid two years earlier, in 1944, when Canadian supporters of the Fourth International met in Montreal for their first national convention.
The majority of the RWP, including Ross Dowson, backed James P. Cannon and the International Committee, while a minority, including Dowson's brother Murray and his brother-in-law Joe Rosenthal led a split from the Canadian section to form the Committee for the Socialist Regroupment of Canada in sympathy with Bert Cochran's Socialist Union of America which had split from the American SWP and sided with Pablo and the International Secretariat.
[5] Members of the former RWP (whose National Committee did not dissolve and whose branches continued to hold meetings) had difficulty working within the CCF.
[2] In 1961, the SEL and SIC merged and became the League for Socialist Action (LSA), with branches in Toronto and Vancouver, with the intention of being the Marxist tendency within the newly formed New Democratic Party (itself a merger of the CCF and Canadian Labour Congress).
Amongst its leadership, Alain Beiner, Ruth Bullock, Al Cappe, Joan Newbigging, John Riddell, Ernie Tate and Art Young were signatories of the 1973 Declaration of the Leninist Trotskyist Tendency, supporting the SWP position in the USFI.
[9] In 1976, Bullock, Riddell, Tate and Young, as well as Dowson (no longer a member of the LSA at this point) were among the signatories of a document, "The Verdict", supporting the SWP leadership against allegations made by Gerry Healey.
[citation needed] In 1977, supporters of the Revolutionary Marxist Group and a separate Quebec organization, the Groupe Marxiste Revolutionnaire, united with the League for Socialist Action and the Ligue Socialiste Ouvrière to form the Revolutionary Workers League/Ligue Ouvrière Révolutionnaire which became the new Canadian section of the USFI.