Prime Minister Scott Morrison has vowed to crack down on GetUp, saying Australian voters wanted the activist group to be more accountable.
Liberal MP Nicolle Flint has accused GetUp of waging a campaign to personally "destroy" her, having been shouted at, posters defaced and office egged during the election.
GetUp has denied being behind any of these actions.
However, Mr Morrison will tell the South Australian Liberal state council that GetUp worked on the principle of "plausible deniability".
"They say they aren't Labor when we all know they are," he will say on Saturday.
"They deny having anything to do with the vile, personal attacks on our candidates that only occur in seats where Getup are running campaigns."
He said the organisation should be ashamed of what happened in Ms Flint's seat of Boothby, as it was "misogyny" and "bullying".
"In this term, we will revisit Getup's claim they are politically independent - because we need to shine a bright light on this shady group that operates in the shadows away from full disclosure," Mr Morrison will say.
"And my message to GetUp is your plausible deniability won't work this term - Australians are on to you."
Parliament's electoral matters committee has launched an inquiry into the 2019 election, including the role of groups such as GetUp, with a report due in mid-2020.
Liberal MPs are expected to make submissions to the inquiry arguing GetUp is a party-political "associated entity" and should be subjected to tougher standards of disclosure relating to its funding and campaign material.
However, GetUp national director Paul Oosting has consistently argued - backed by a series of previous inquiry reports - his organisation is a "political campaigner" and not associated with any political party.
"We go above and beyond what the law requires us to report and have lifted the standards of transparency in politics. We wish the Liberal party would do the same," he told AAP last week.
Australian Associated Press
