Preference whisperer Glenn Druery brokers deal between Derryn Hinch and Labor

The preference deal will likely boost the chances of Justice Party candidates joining the former broadcaster in the Senate, however Labor has said it made no policy promises in exchange for the influential crossbencher's support.

The major parties have been in fierce negotiations with smaller players ahead of the start of early voting on Monday, with a formal deal between the Coalition and mining magnate Clive Palmer to be announced this week.

Labor's deal with Senator Hinch will be made public on Monday when candidates start distributing their how-to-vote cards at pre-polling stations as the campaign enters its final three weeks.

In exchange for Justice Party's preferences in the seats of Casey, Macnamara and Corangamite, Labor will encourage its voters to place Senator Hinch-aligned candidates second on the Senate ballot. A Labor source said the party had not made any policy promises to Senator Hinch.

"We recognise that [Derryn Hinch] has a high profile in Victoria and is much more open to negotiations than the Greens," the source said.

"He is much more pragmatic. And the preference [deal] is about taking votes from the right-wing column."

Labor is hoping an alliance with a "pragmatic" Senator Hinch will boost its chances of passing controversial legislation, including changes to superannuation tax and industrial bargaining reforms, through the Senate.

A recent Australia Institute polling found that the "best case" scenario for a Coalition government would be to deal with at least two minor parties to pass its legislation, while the "best case" for Labor would be to rely on Centre Alliance from South Australia.

But Australia Institute director Ben Oquist said while the deal could be mutually beneficial, it would be highly unlikely to have a "substantial effect unless the contest was very tight".

"While preferences could help at the margin, the new voting regime for the Senate means they count a lot less," Mr Oquist said.

Senator Hinch said his party was more centrist than others headed by Fraser Anning, Cory Bernardi and Pauline Hanson.

"So I think, compared to those parties, it gives them a fairly good choice to preference us ahead," Senator Hinch said of Labor.

Mr Druery, a staffer for Senator Hinch, was involved in complex negotiations over preferences with a string of minor parties in the Victorian state election and the 2013 federal election.