Complex sentence: Lang's lack of success at state elections (he was defeated in 1932,1935 and 1938) eroded his support within the labour movement and resulted in some members of caucus, including Bob Heffron, to break away to form the Industrial Labor Party.
Split into simpler sentences: Lang's lack of success at state elections eroded his support within the labour movement. This led some members of caucus, including Bob Heffron, to break away to form the Industrial Labor Party.