One of Victoria's most powerful unions has unleashed 150,000 robocalls on three marginal Labor seats in a bid to save 250 timber mill jobs.
The CFMEU is also pushing out targeted ads on social media as it aims to keep the Heyfield timber mill open.
The Gippsland mill's owners rejected the state government's reduced wood supply offer in March, deciding to close the mill in 2018 instead of operating with fewer logs.
"Our members are being left hanging and we won't cop it. It is soul destroying to leave people not knowing what the future will bring," CFMEU Victorian district secretary Frank Vari said on Tuesday.
"The government needs to know that the union, our members and supporters will keep up the pressure to save these jobs, save the town of Heyfield and save the wider community that relies on these jobs."
The CFMEU made 150,000 robocalls in the electorates of Monbulk, Mordialloc and Narre Warren South on Monday night.
Premier Daniel Andrews offered to buy the mill and keep it going if the owners didn't believe they could make it work, but Australian Sustainable Hardwood said 200 jobs would be lost if the mill had to operate with reduced wood supply.
The CFMEU is strongly linked to former Emergency Services Minister Jane Garrett, who quit cabinet after a showdown with Mr Andrews over a controversial firefighters pay deal.
Now a backbencher, Ms Garrett has refused to rule out a tilt at the Victorian Labor leadership in the future.
Deputy Labor leader James Merlino holds Monbulk by five per cent, Tim Richardson holds Mordialloc by two per cent, and Judith Graley holds Narre Warren South by five per cent.
Labor holds a two seat majority in the Victorian lower house.
