A John Setka-backed challenger to CFMEU leader Michael O'Connor allegedly drove his union car through a Melbourne home, narrowly missing a sleeping elderly woman before fleeing the scene and sparking a police manhunt.

The allegations have emerged as part of a bitter struggle over the Construction, Forestry, Maritime, Mining and Energy Union's manufacturing division, where Setka's construction branch has sought to unseat Mr O'Connor as division head in upcoming elections.