But on Monday a Labor source told Fairfax Media: "We are preferencing progressive parties above the Liberals and putting One Nation last everywhere." "I've brought the big parties together – their duopoly is under attack.": Nick Xenophon. Credit:Pat Scala A separate Labor figure denied this exposed Labor to the same criticisms it made of the Liberals because the Greens had never won a lower house seat on Labor preferences – only Liberal. Mr Turnbull exerted his authority on the weekend when he declared the Liberals would preference the Greens last across the country. His declaration cames months after suggestions from the Liberal Victorian Party president Michael Kroger that the party could enter into a loose vote-swap deal with the Greens, which would see Liberal preferences flow to the Greens in inner-city seats held by Labor, in exchange for Greens preferences in outer-suburban seats where Labor is vulnerable to the Coalition. Mr Kroger claimed the Greens had changed and were "not the nutters they used to be."

But the Prime Minister has since campaigned strongly against the minor party, warning their policies would be a disaster for the Australian economy and jobs. Malcolm Turnbull declared on the weekend the Liberals would preference the Greens last across the country. Credit:Andrew Meares The Greens had been hoping to replicate the 2010 deal in which Liberal preferences helped the lower house MP Adam Bandt win the seat of Melbourne from Labor. Mr Bandt went on to help Julia Gillard form a minority government between Labor, the Greens and the independents. But the Liberals' decision to reverse their preferences in 2013 failed to oust the Greens from the seat, which Mr Bandt won after polling above 40 per cent in the primary vote. In April, the Labor MP for Melbourne Ports Michael Danby rubbished Mr Kroger's suggestions the Liberals could deal with the Greens and said unlike the Liberal Party official, he would show leadership.

"I, as in the last election, am determined that in my seat that I will be preferencing the Liberals ahead of the Greens party, " Mr Danby said. "I don't think Senator Rhiannon's national security policies, I don't think Senator Di Natale's irresponsible economic policies … are things that my electorate supports. "And I want to show some leadership by saying that Michael Kroger's unprincipled, opportunistic stance – you won't get the same from Danby." If the Liberals has preferenced the Greens in New South Wales it would almost certainly have seen the popular Labor frontbencher and one-time candidate for leader Anthony Albanese voted out of Parliament. In March he decried any suggestion of a Liberal-Labor deal as the "ultimate example of cynical politics and putting tactics before principle".

Senator Xenophon hit out at what he claimed were the "dirty preference deals" struck by the major parties and demanded Labor and Liberal say whether they will swap votes with each other and "lock out" his party. Neither side has said who they will preference in South Australia, where Senator Xenophon could potentially win three seats from the Liberals, including the seat of Mayo, held by former junior minister Jamie Briggs who was forced to quit after an incident in a Hong Kong bar. The Labor source said: "There is no deal from Labor to preference the Nick Xenophon Team or the Liberals in SA," meaning the door is still open to a potential deal. Senator Xenophon said his party is maintaining its position to run open tickets for all seats but "reserved the right to revisit that position if the major parties do this deal." He is threatening the so-called "nuclear option", which would see NXT votes directed against the incumbent MP in all lower house seats if the major parties preference swap each other. Neither Labor nor Liberal sources were willing to go on record about any negotiations with the Nick Xenophon Team.