For a number of years, Cochran was part of the National Committee, the leading body of the SWP and became the party's main leader in Detroit.
In the 1930s and 1940s, Cochran was a district organizer for the Mechanics Educational Society of America (MESA), a radical independent union which drew the ire of the federal government for refusing to not strike during World War II.
The faction, known to their opponents as the Cochranites, argued that the SWP was abstaining in a sectarian manner from the opportunity to intervene into the radical layers around the Communist Party.
The SWP's leadership interpreted this as meaning that the current around Cochran no longer believed a revolution in the United States was possible, and that they had recoiled from revolutionary activity under the dual pressures of relative post-World War II capitalist prosperity and the accompanying McCarthy-era anti-communist witch-hunt.
Eventually, Bert Cochran and the Cochranites were expelled from the SWP in 1954, which meant that the party lost a great deal of its members in Detroit and the Cleveland area.