The 2016 federal election produced a large and diverse crossbench, with three minor parties winning three or more seats, while four other parties won a seat each. The double dissolution election made it easier for small parties but the trend is likely to reverse in 2019, with many of these crossbenchers in difficult races.

While the crossbench is large, the balance of power in the Senate is generally held by a group of senators who sit close to the centre (or at least defy classification), including the Centre Alliance, Derryn Hinch and Tim Storer. This election gives the Greens a narrow chance of grabbing the balance of power, but it’s more likely that a bloc of centrist senators will remain crucial to the next government’s agenda.

There are two main questions we should be asking about this Senate election: which minor parties are in with a chance of holding or gaining a seat, and who will hold the balance of power and have the most influence over legislation?

The minor-party contests

The 2016 election was a double dissolution, with the entire Senate up for election. Since each state was electing 12 senators rather than the usual six, the quota for election was substantially lower, making it easier for minor parties to win seats. The election resulted in a record high vote for minor parties, with more than 35% of votes in the Senate cast for parties other than Labor or the Coalition, and saw 20 crossbench senators elected. Most of these crossbenchers only have a three-year term, so will be up for election this year.

One Nation will be running Malcolm Roberts, pictured, against Fraser Anning, who replaced him in the Senate. Photograph: Mike Bowers/The Guardian

The Greens are defending seats in all six states. They will be fighting to hold on to seats in New South Wales, Queensland and South Australia.

One Nation won four seats in 2016, but only hold two of those seats now. They will be hoping to regain their seat in Queensland. They are running Malcolm Roberts against Fraser Anning, who replaced him in the Senate and promptly quit the party. Anning is unlikely to win but Roberts will also be up against the third Liberal National candidate and Clive Palmer.

There are currently two rightwing minor party senators in New South Wales, and probably only space for one of them to be re-elected. Brian Burston is running for Clive Palmer’s United Australia party after leaving One Nation, while Duncan Spender replaced David Leyonhjelm as the Liberal Democrats senator when Leyonhjelm left to run unsuccessfully for the NSW upper house. One Nation’s Kate McCulloch will also have a shot, as will the Nationals’ Perin Davey.

Derryn Hinch ended up polling just enough in 2016 in Victoria to have won a seat if the election was a half-Senate election but a lot will depend on the relative strength of the other parties and his ability to pull preferences this time round. He could be defeated by the third Liberal or third Labor candidate.

Jacqui Lambie is attempting a comeback in Tasmania, aiming to regain the seat she lost over her citizenship issues. Her successor, Steve Martin, will be running for the Nationals. They will each be competing with the third Liberal and Labor candidates for the final seat.

The Liberal party will have a challenge on their hands holding on to their three South Australian seats. Labor holds just one seat and should gain at least one. Independent senator Tim Storer is retiring, and the Centre Alliance would be hoping to regain his seat. If Labor and Centre Alliance each gain a seat, one of those seats would either be at the expense of the Greens’ Sarah Hanson-Young or the third Liberal.

The Greens leader, Richard Di Natale, and Greens senator Sarah Hanson-Young campaign at Adelaide Koala and Wildlife hospital in Adelaide. Photograph: Kelly Barnes/AAP

One Nation senator Peter Georgiou will be facing off against the third Liberal candidate to hold on to his seat in Western Australia, and will likely need to poll more than One Nation did in 2016 to pull it off.

Who will hold the balance of power?



While there are a number of contests between various rightwing candidates in each state, Labor and the Greens will be hoping that a national swing to the left will strengthen their position, and give a potential new Labor government more options in passing legislation.

In normal half-Senate elections, progressives usually win three seats in each state, with conservatives winning the other three seats. For one “side” to win a fourth seat would require up to 57% of the vote, which is rare. Of course some parties don’t fit within these categories, such as the Centre Alliance, and there are exceptions when a party achieves a landslide result.

Labor and the Greens come into this election with 35 out of 76 senators. Centrists such as the Centre Alliance, Hinch and Storer hold four seats between them. The other six crossbenchers are more conservative and unlikely to be particularly cooperative with a new Labor government. So if current numbers hold, and Storer is replaced by Centre Alliance, Labor or the Greens, then there would be enough votes between the centrist crossbenchers, Labor and the Greens to pass legislation. Every extra seat Labor can win off a conservative strengthens its position and gives it more options.

So what prospects are there for progressive gains?

Labor and the Greens only hold two seats in New South Wales, and hold four in Tasmania. They should win at least three in each state, and there is some chance of them winning a fourth in Tasmania if they do particularly well.

The balance of power in the Senate is likely to remain with a group of senators from the Centre Alliance potentially alongside others such as Derryn Hinch, pictured, or Jacqui Lambie. Photograph: Mike Bowers/The Guardian

They have a chance of picking up a third seat in South Australia, either the open seat vacated by Storer or from the Liberal party. If there is a big swing away from the Coalition in Victoria it may be possible for Labor to gain an extra seat there without taking it away from the Greens.

There is also a possibility that the left could gain an extra seat in the Australian Capital Territory. Each territory only elects two senators, and until now it’s never been possible for the Greens to take a seat off the Liberal party but in current circumstances the Liberal senator Zed Seselja, a social conservative who backed Peter Dutton, may be vulnerable in the progressive ACT.

Between Tasmania, Victoria, South Australia and the ACT there are four opportunities for the left to gain an extra seat. If all four of these were to flip to Labor or the Greens, it would give these two parties a majority between them, giving more options for passing legislation. But this would require a very strong result, and it’s not likely that all of these races will go this way.

What is more likely is that the balance of power in the Senate will remain with a group of senators from the Centre Alliance potentially alongside others such as Hinch or Lambie.