A former ambulance union boss has answered Labor's emergency call after the party dropped its candidate for the safe western suburbs seat of Melton on Thursday.

Steve McGhie, retired state secretary of the Ambulance Employee Union, will contest the seat of Melton after preselected candidate Justin Mammarella abandoned the race with just four weeks until polling day. It is understood party bosses forced his hand.

Steve McGhie during his time as president of the National Council of Ambulance Unions with paramedics in Canberra. Credit:Elesa Kurtz

Melton is held by Don Nardella, who has sat on the cross benches in State Parliament since he resigned from the ALP in 2017 after being caught rorting his second-home allowance.

With Mr Nardella not contesting Melton next month, the seat is expected to remain safe Labor territory in November’s poll.