The Andrews' government has done a back room deal with the Animal Justice Party in a bid to secure a Labor victory in Saturday's crunch byelection in Northcote.

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.

Nina Lenk, Animal Justice Party candidate in the Northcote byelection. Credit:Daniel Pockett

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.