He became increasingly involved in Democratic politics, and chaired the Labor Bureau of the Democratic National Committee in 1932, 1936, 1940, and 1944. His re-appointment in 1936 by DNC chair James A. Farley deeply upset the leadership of the Congress of Industrial Organizations (CIO), who felt Tobin an uninspired campaigner and strategist. In response, the CIO formed Labor's Non-Partisan League to fully and completely mobilize labor support for Roosevelt. But despite the division in the American labor movement, by 1944 Tobin was working closely with the CIO PAC.