The Liberal party has conceded targeting an independent candidate's criminal conviction has backfired in the Tasmanian seat of Braddon.
Fisherman Craig Garland polled strongly in the north-western electorate, securing 10.6 per cent of the primary vote, with his preferences helping Labor reclaim the seat.
Late in the by-election campaign, the Liberals attacked Mr Garland's criminal conviction for assaulting a female off-duty police officer in the mid-1990s.
The move pushed Mr Garland to publicly endorse Labor, and it is understood Tasmanian Liberals agree it backfired on them.
The tactic was devised by central party strategists and saw Tasmanian senators publicly criticise Mr Garland.
Failed Braddon Liberal candidate Brett Whiteley said the life of anyone who stands for public office ought to be forensically scrutinised by the media and public.
"I'm not going to comment on whether something was a mistake or not," Mr Whiteley told reporters on Sunday.
"I've already said I respect the fact that he and every other candidate were gutsy enough to put their name on a ballot paper, and I encourage people to step up to the plate in democracy."
Labor's Justine Keay said both major parties should pay close attention to the strong support for Mr Garland.
"I think the people looked at someone that had something a little bit different to offer, and I think we should all learn from him," she told reporters.
"He pulled a very high vote and I think that's something all the major parties need to look at."
Mr Whiteley has now been rejected twice in two years, but didn't rule out seeking preselection for the next election.
Tasmanian Liberals president Geoff Page described the by-election result as disappointing, and there will be much to say about the campaign strategies and tactics.
"But at the end of the day, while unsuccessful, we have out-performed history, and that is something we can all be proud of," Mr Page said in a statement.
"A large number of people have made it clear they are unhappy with the performance of both major parties, and we must acknowledge that and take their concerns on board ahead of the general election next year."
Ms Keay is expected to finish with more than 52 per cent of the vote.
She won the seat from Mr Whiteley in 2016, was forced to stand down in May after failing to renounce her British citizenship in time for the election.
Australian Associated Press