This article is more than 1 year old

This article is more than 1 year old

Simon Birmingham has lashed out at Liberal-turned-independent Julia Banks for preferencing Labor ahead of the Coalition in Flinders, a move which could cost health minister Greg Hunt his seat in parliament.

Birmingham accused Banks of “gross inconsistency”, as backroom negotiations spilt out into public spats ahead of early voting opening on Monday.

Labor has gone on the offensive over preference deals between the Coalition, the United Australia party and One Nation, as a new Galaxy poll showed the major parties were treading water in the campaign while Pauline Hanson’s party was falling behind.

But in Flinders, held by Hunt with a 7% margin, Labor is the beneficiary of a preference deal with Banks, who quit the Liberal party and shifted from her seat of Chisholm to run as an independent after Malcolm Turnbull was dumped as prime minister.

On Sunday, Birmingham, the Coalition campaign spokesman, said voters would “really have to wonder about the various positions of Julia Banks, who was until not that long arguing people to vote Liberal and is now suggesting she will preference Labor”.

“That is up to her to explain and to justify, but I think it shows a gross inconsistency on her behalf,” he said, accusing Banks of “walking away” from her principles and the seat of Chisholm.

On Thursday the Coalition concluded a preference deal with the United Australia party, which will boost the Coalition in key marginal seats and could see Clive Palmer enter the Senate in Queensland and Brian Burston re-enter the Senate from the top of the party’s ticket in New South Wales.

A Galaxy poll of 1,012 voters conducted from Tuesday to Thursday found Labor leading the Coalition 52% to 48% in two-party-preferred terms, in line with both the most recent Guardian Essential poll and the latest Newspoll.

The poll found the Coalition’s primary vote is up 2% to 37%, but well below the 42% primary vote at the 2016 election which saw it returned with a slim one-seat majority.

Shorten promises cheaper childcare as Morrison pledges refugee intake freeze Read more

While Labor is steady on 37% and the United Australia party remains on 4%, One Nation has collapsed from 8% to 4%.

On Sunday Labor muscled up to Palmer, with Labor leader in the Senate, Penny Wong, targeting him for describing the Chinese government as “mongrels” in 2014.

At the launch of Jennifer Yang’s campaign in Chisholm, Wong labelled Palmer a “con man” because of the unpaid wages bill at Queensland Nickel where workers are owed $7m, which Palmer says he has set aside in a trust fund, and the $67m wages bill picked up by taxpayers.

Speaking to Insiders on Sunday, the Labor deputy leader, Tanya Plibersek, questioned what Palmer had “extracted from Scott Morrison to get this deal”.

Plibersek targeted Morrison for “doing deals with minor and rightwing parties that will cause chaos – chaos in the Senate if they’re elected”.

Although the Liberals have ruled out giving preferences to One Nation, Plibersek noted that the Nationals are dealing with Hanson’s party.

Plibersek attacked Palmer, accusing him of being “lazy” for only attending 25 of 400 votes held when he was an MP in the 44th parliament, and noting that when his party had three senators elected in 2013 they “ended up with three different political parties” due to Jacqui Lambie and Glenn Lazarus quitting his party.

“I think Clive Palmer will come under increasing scrutiny during this campaign and people will ask themselves why they would vote for a man who dudded his own workers,” Plibersek said.

'You will get up with fleas': Bill Shorten attacks Liberals' deal with Clive Palmer Read more

But Plibersek was also forced to defend the fact Labor figures including senator Anthony Chisholm and unionist Michael O’Connor reportedly reached out to Palmer to discuss preferences.

She said “a couple of SMSs” were not formal negotiations and Labor had made clear it would never do a deal with Palmer while workers were out of pocket.

The United Australia party is emerging as a threat in the Senate to Labor legislating its taxation policies.

Burston told Guardian Australia the United Australia party will “likely oppose” most of Labor’s economic policies, criticising the proposed $34bn impost on superannuation and the decision to stop cash rebates to self-funded retirees for excess franking credits.

But he said the party “may” make an exception for policies that “cater for those who have already invested”, such as the negative gearing and capital gains tax policies, which are grandfathered.

Burston has rejected claims the United Australia party could elect candidates who might then abandon the party, as occurred under the Palmer United party.

“Back then [Palmer] was a bit rusty in selecting candidates,” Burston told Guardian Australia.

“This time it’s taken place over many, many months, they’re well vetted, there’s procedures in place where the falling apart … of the party will not happen. It cannot happen, or there’ll be consequences for those that want to walk.”

Burston said the party had “various strategies in place to prevent that happening” including “signed contracts”.