Launch guests included Member for Western Victoria Jaala Pulford and Labor candidate for Mildura Shane Roberts.

Mr Scates described himself as an underdog with a capital 'U'.

He said increasing public transport across the electorate would be a focus of his campaign.

"The Coalition's record on public transport under Baillieu and Napthine is very, very poor," he said.

"It's all very well at five minutes to midnight saying we're going to pour money into public transport."

Mr Scates criticised the lack of protest from within the government after Overland train services were cut.

"It's a great service and that got cut to two services a week," he said.

"Not one National Party member stood up in Parliament and said 'that's disgusting - we don't want our main Adelaide to Melbourne train service downgraded'," he said.

Ms Pulford paid tribute to Mr Scates, 64, whom she said had spent many years devoted to the Labor party.

"Bob has been for many, many years a tireless campaigner for social justice," she said.

"He has been a vigorous supporter of public housing and lived a life characterised by social justice."

Mr Scates will contest the seat against the National Party's Emma Kealy and Independent Katrina Rainsford.