Animal Justice confirmed on Friday it had agreed to direct preferences to Labor in return for more than $500,000 of taxpayer-funded spending on the micro party's favoured causes.

Preferences could be decisive in the vote and Labor has brokered a separate deal with another minor party, the Liberal Democrats, who will also direct preferences away from the ALP's Greens opponents.

The arrangement will see ALP volunteers distribute the Liberal Democrats how-to-vote cards at polling places on Saturday.

The latest Reachtel poll - commissioned by the CFMEU - shows Labor in a winning position, with preferences from the animal rights outfit and the Liberal Democrats likely to get ALP candidate Clare Burns over the line ahead of Greens challenger Lidia Thorpe.

But the Greens still believe they can take Northcote, left vacant by the death of government minister Fiona Richardson, in Saturday's byelection.

The government's announcement on October 19, of a public sector group called Animal Welfare Victoria which would splash $500,000 on animal welfare causes in its first year of operation, attracted little attention.

But AJP Candidate Nina Lenk??? told The Age on Friday the funding was offered in an effort to lure the micro-party party away from its traditional loose affiliation with the Greens.

Animal Justice attracted about 1.75 per cent of the primary vote in Northcote in the 2014 election.

But the party's deal with Labor has come as a psychological blow to the Greens, who won the seat of Prahran in the tightest of races 2014 in part on the back of Animal Justice preferences.

On the campaign trail on Friday, Ms Lenk said there was no rift with the Greens, but that Labor had sweetened the deal for the AJP.

"We're preferencing Labor because they were offering us a Victorian welfare group for animals, they were also offering us about $500,000 for animal organisations and community organisations," Ms Lenk said.

"Clare, the candidate, is vegan too and we obviously really identify with those values as well and they're going to re-align the prevention of cruelty to animal acts.

"So basically that's why we gave our votes, our preferences to Labor."

Labor's animals package also include a review of the Prevention of Cruelty to Animals Act with the intention of replacing the laws with a "modern animal welfare act" by 2019.

A government spokesman said Labor was following up on its animal welfare election promises.

"Our record when it comes to animal welfare is second to none," the spokesman said.

Despite the polls and the preference deals, the race remains tight in Northcote where Labor's margins have been steadily eroded by the Greens since they first emerged as an electoral threat 15 years ago.

Monash University political scientists Nick Economou??? said sitting governments were often at risk of a "kicking" in byelections but the Northcote result was extremely difficult to call.

"In a tight race, the fact the Animal Justice Party is directing preferences away from the Greens could be hugely significant," Dr Economou.

Ms Thorpe would not be drawn on the question of preferences deals but said she was proud of her campaign.

"We've seen the Government shift towards progressive Greens policies, which we all welcome, but we shouldn't have had to wait for a byelection for action on schools funding, the environment or renters rights."

Liberal Democrats candidate Dean Rossiter said his party's decision on preferences was a simple one.

"The Greens are worse, they're more fervently communist than the Labor Party," Mr Rossiter said on Friday.