Scott Morrison has stressed his government won't be hatching policy plans with controversial businessman Clive Palmer, regardless of whether it mints a preference deal with his political party.
But Labor insists the coalition must have promised Mr Palmer something to have earned his favour.
The prime minister says Australians will learn within days about any preference deals the Liberals have struck, once they have been settled.
Mr Palmer's United Australia Party is expected to form an agreement with the Liberals, which could boost his chances of returning to federal parliament after the May 18 election.
That comes as the businessman remains under fire for not paying $7 million in workers' entitlements after his Queensland nickel refinery collapsed in 2016, while spending more than $30 million on election advertising.
Mr Morrison noted he and Mr Palmer, who is running as a Senate candidate in Queensland, share the view that a Labor government led by Bill Shorten would damage the economy.
"There is quite a bit we don't agree on at all, but he makes a good point when he says that," the prime minister told reporters in Townsville on Friday.
But the leader stressed the Liberal-Nationals have made no "policy deals" with minor parties such as UAP.
"There has been no discussion with the minor parties on policy. Absolutely none."
Labor leader Bill Shorten argues the coalition must have promised Mr Palmer something in exchange for a good spot on their "how to vote" cards.
"The idea that it's just a non-exchange arrangement with Clive Palmer would be the first time in human history," he told reporters in Melbourne.
Senior Labor frontbencher Penny Wong said Australians should not forget the "chaos" that evolved from Mr Palmer being elected to parliament in 2013.
Cabinet minister Mathias Cormann earlier accused Labor of being "high and mighty" about deals with UAP, noting reports a senator and senior union heavyweight negotiated with Mr Palmer about how-to-vote cards.
"We are doing everything we can to maximise the voting support across seats across Australia - as the Labor Party is doing," the senator told Sky News on Friday.
But Labor has dismissed suggestions a senior union figure was sent to negotiate preferences with Mr Palmer.
"There've been no formal negotiations," Mr Shorten said.
United Australia Party senator Brian Burston told the ABC internal polling showed they were on track to win as many as six Senate spots, which would guarantee Mr Palmer's return to Canberra, as well as pick up lower house seats.
Published opinion polls put the party's national support at two per cent.
Australian Associated Press