Some say that Americans downplayed political and social agendas for the sake of unity, so that short-term gains and building strong unions came at the cost of a potential labor party.
After he failed to persuade the UAW Convention in 1937 to give him authority to fire organizers and eliminate local union newspapers, Martin set out to expel his rivals.
After firing or transferring a number of CP members who had played prominent roles in the Flint sit-down strike, Martin first suspended, then expelled, Mortimer and his other opponents on the UAW's Executive Board.
The CIO leadership, alarmed by the possibility that sectarian infighting might destroy the UAW, forced Martin to reinstate the Executive Board members.
But that would have required that the Party defy Sidney Hillman, head of the Amalgamated Clothing Workers of America and the most powerful force within the CIO after Lewis, and Philip Murray, Lewis' protégé and head of the Steel Workers Organizing Committee, who came to the convention to demand the selection of R.J. Thomas, an apolitical Board member who had, until recently, supported Martin, as its candidate to end the factional fighting within the UAW.
Eager not to appear as sectarians and thus endanger their role within the CIO at large, the CP leadership had the Communists within the UAW support Thomas and also permit the elimination of the Vice-President positions that they had held.
What is more, the CP now repudiated its Popular Front strategies of the previous four years, attacking President Franklin Delano Roosevelt's administration's efforts to support France and Britain against Germany as a campaign to lead the US into an imperialist war.
At the same time that their break with Roosevelt isolated them within the CIO, opponents of the CP outside the labor movement stepped up their attacks on the loyalty of Party members, accusing them, among other things, of engaging in sabotage by supporting strikes of aircraft workers during the UAW's organizing drive in that industry.
At the same time Lewis abolished the position of west coast director of the CIO, which Harry Bridges had held, limiting his authority to California.
So while internal political disputes kept the battles raging within unions such as the UAW, the UE and the IWA, the CP agreed to a compromise that forced them to accept the label of "totalitarian," but allowed them to maintain their positions within the CIO itself.
Strikes at Harville Die-Casting Company, Alcoa, and North American Aviation were widely seen within the Roosevelt administration as communist-inspired for ideological reasons, rather than for better wages and working conditions.
When A. Philip Randolph, President of the Brotherhood of Sleeping Car Porters and the foremost African-American unionist of the time, urged a march on Washington in 1941 to underscore black workers' demands for the elimination of job discrimination in war industries, the CP attacked him relentlessly.
In the end, the 1943 UAW Convention defeated both sides' proposals on a voice vote after a heated debate in which many delegates opposed taking any stand on civil rights as being outside the union's economic sphere.
The CIO and the AFL each supported the pledge in general, particularly after the furor strikes in the aircraft industry and at Allis-Chalmers Company had provoked in the years immediately before the United States' entry into the war.
Bridges, Joseph Curran of the NMU and Julius Emspak of the UE even supported a proposal by Roosevelt in 1944 to militarize some civilian workplaces, but retreated when the rest of the CIO executive board reacted furiously against it.
Walter Reuther used this issue to great effect against the CP and its allies at the UAW's 1943 Convention, where his slate fell just short of defeating Addes and Frankensteen.
The most serious was their complete rout in the UAW, where Walter Reuther's slate finally triumphed in 1947 after years of inconclusive struggles with the Addes and Frankensteen faction.
Reuther subsequently drove all of his principal CP adversaries out of the UAW, using one of the provisions of the newly enacted Taft–Hartley Act to complete the process.
Murray might have let the status quo continue, even while Reuther and others within the CIO attacked Communists in their unions, if the CPUSA had not chosen to back Henry A. Wallace's third party campaign for President in 1948.
Murray began by removing Bridges from his position as the California Regional Director for the CIO and letting go first Len De Caux in late 1947 and Lee Pressman in early 1948.
Anti-communist unionists then took the battle to the City and State Councils, where they attempted to oust Communist leaders who did not support the CIO's position on the Marshall Plan and Wallace.