The last Queensland election, in early 2015, saw the election of a new Labor government after one term of Liberal National government. The LNP had won a landslide victory in 2012, but a swing of 14% back to Labor gave it two more seats than the LNP, and a deal with an independent brought the party back to power.

Polls have generally indicated the election will be close, with most polls putting the parties between 48% and 52% after preferences. The latest Newspoll put Labor on 52% after preferences, while a recent ReachTel poll gave 52% to the LNP.

One Nation has also been polling well all year. The party began to perform more strongly after its surprise result at the 2016 federal election. It polled above 20% in a pair of polls at the beginning of 2017, and over the course of the rest of the year has polled between 15% and 18%.

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The presence of One Nation makes it hard to analyse the polls – it’s not clear how those One Nation preferences will flow, between Labor and Liberal National. Roughly half of One Nation preferences in the last federal election flowed to Labor, and their preference recommendations can make a big difference.

One Nation first broke through at the Queensland state election in 1998, when they polled above 22% and won 11 seats. The party is not polling quite as well this year, but if they manage 15%-18% of the vote they would likely win a handful of seats. A lot will depend on how many preferences they receive from the major parties, and whether they can hold on to their vote. Polling before this year’s Western Australian state election predicted a One Nation vote well over 10%, but the party managed just over 8% in the upper house.

Katter’s Australian Party (KAP) and the Greens are also hoping to have an impact in the next parliament. KAP holds two seats in north Queensland, although one of them is more vulnerable after the redistribution. The Greens do not hold any seats, but are targeting a number of inner-Brisbane electorates, buoyed by their first breakthrough on Brisbane City council last year.

A change in the voting system also makes it harder to predict this election. Until 2015, Queensland voters were not required to mark preferences on their ballot – if they chose to do so, they could just vote 1. This traditionally meant that many minor party voters did not end up making a choice between the major parties – One Nation voters in 1998, and the Greens more recently. The law was changed in the last term to make preferences compulsory, which means more of those preferences will flow.

Queensland’s electoral map has been redrawn since the last election, increasing the seats from 89 to 93. This increased Labor’s seat count by four, while the other parties maintained their existing seats. This means that Labor would have won a majority of the new seats on the results of the last election.

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But Labor can’t count on all of the seats it won in 2015. Three of the MPs who won seats at the last election are no longer members of the ALP: Billy Gordon in Cook was expelled in 2015, and Cairns MP Rob Pyne quit the party in 2016. Controversial Pumicestone MP Rick Williams was disendorsed late last week, leading to his resignation from the party.

This election looks set to be close. Most polls have been very close, with both major parties taking the lead over the course of the last year. The One Nation vote will make the election more complex, with One Nation preferences potentially deciding the winner in marginal seats, and the party hoping to pick up a swag of seats. If One Nation’s vote holds up and they can win a number of seats, a close election could lead to a hung parliament, with One Nation playing a critical role.