Minor parties face an uphill battle to be elected, with a state calling time on a controversial voting system that allowed harvesting of preferences through backroom deals.

Group voting tickets have been abolished in Victoria for the November state election after the upper house passed reforms.

Victoria was the only Australian jurisdiction still using the system, which enabled parties to re-distribute preferences to other upper house candidates when people voted above the line.

It has been replaced with preferential voting above the line, giving voters the power to pick  multiple parties and bringing Victoria's upper house into line with the Senate.

Shooters, Fishers and Farmers Party's Jeff Bourman, Libertarian Party's David Limbrick, Legalise Cannabis Party's Rachel Payne and Animal Justice Party's Georgie Purcell were the only four upper house MPs to vote against the changes.

Ms Purcell, who has become one of Victoria's most recognisable political figures since being elected in 2022 with 1.53 per cent of first-preference votes, on Wednesday acknowledged the reforms would "significantly decrease" her chances of re-election.

"Nobody wants group voting tickets, but we didn't want rushed electoral reform on the eve of an election either," said the Northern Victoria MP, who is vowing to fight on.

"For eight years now, the Animal Justice Party, and all minor parties in the parliament, have been calling on the government to undertake this work in the right way, but our attempts to work collaboratively have been ignored."

Voting manipulation was laid bare before the 2022 state election after "preference whisperer" Glenn Druery was covertly recorded boasting about his method and outlining a $55,000 fee.

A Labor-chaired inquiry in December recommended a "two-step process" for reform, with group voting tickets eliminated this term and possible changes to the structure of the eight-region upper house pushed off to the next four-year cycle.

Any structural change to the 40-seat Legislative Council would require a referendum.

Ms Payne, who is also vying for re-election, described the partial enactment of the recommendations as a "dark day for democracy" and conceded the reforms would make it harder for smaller parties to win seats.

"It will undoubtably turn the upper house conservative and ... lock in a monopoly of the big parties," she told reporters.

Polling indicates One Nation's primary vote is hovering in the 20s, meaning it could reach the vote quota of 16.7 per cent to get candidates elected in every upper house region on first preferences alone.

That would likely leave One Nation with the balance of power in the upper house next term.

Victorian One Nation MP Rikkie-Lee Tyrrell said the voting reform was unlikely to make a major difference to the party's election prospects in November.

"What does make a difference is that it's putting the power of the vote back into the hands of Victorians," she said.