As Australians head to the polls, some high-profile senators, including One Nation Leader Pauline Hanson and Liberal Eric Abetz, are in the fight for their political lives.
The makeup of the Senate can have a big impact on a government's ability to get its agenda through.
For the past three years, the Coalition has been three seats short of a majority, relying heavily on the crossbench, particularly the two One Nation senators, to pass legislation.
In Queensland, Pauline Hanson is up for re-election against a bevy of right-wing candidates, including Clive Palmer and former Premier Campbell Newman.
Election analyst Dr Kevin Bonham said Ms Hanson is likely to regain her seat, with the third spot Liberal National Partly (LNP) candidate, Amanda Stoker, the most likely to miss out.
"If there is a seat lost on the right, I think it is more likely the LNP seat at this stage," Dr Bonham said.
"But we don't know, One Nation is bit of an unknown quantity."
Dr Bonham does not believe Clive Palmer nor Campbell Newman will have much of an impact.
"There has always been a lot of speculation about all … the anti-mandates, anti-lockdown anti-vax sort of crowds and that they might turn out for One Nation," he said.
"But, really, there is actually quite a lot of parties competing for support of that group and they are quite disunified."
And Dr Bonham does not think Labor will see a repeat of 2019, when they lost their second Senate spot in the Sunshine State.
"It will be a little bit surprising if Labor did badly enough to, again, miss out and only get one seat."
The race will depend a lot on what is happening nationwide according to Dr Bonham.
"Labor's aim, if they've managed to form government in the lower house, will be to try to improve their position so that they would not have to rely on One Nation to pass anything."
Green balance
But that is no guarantee and how colourful the crossbench could be and how much power they may have is up for grabs.
The Greens have their eye on picking up three seats in the upper house, with a bold ambition of taking their Senate party room to 12 at this election, up from nine.
"They have good prospects to pick up senate seats in most, if not all states," Dr Bonham said.
"They have three that they are actually defending, so they won't gain any more in those but the other three, they have chances in."
Greens leader Adam Bandt is campaigning on the ambition of holding the balance of power in the Senate, with a raft of demands.
"The Greens will push for a freeze on new coal and gas projects so that we can tackle the climate crisis, but also to tackle the cost of living," Mr Bandt said.
"We want to get dental and mental health into Medicare, wipe student debt and fix the housing affordability crisis."
Their forthright demands have been criticised by many, but Mr Bandt said they are just being honest.
"What we are doing is being up-front with people about what would happen if there is a power share in parliament."
Below the line
In Tasmania, veteran Liberal Senator Eric Abetz has been relegated to third spot on the senate ticket, which could likely see him bow out of federal parliament after 28 years.
Dr Bonham said Senator Abetz is likely to lose, with the last seat a competition between a third Labor senator, the Jaquie Lambie Network candidate and, possibly, One Nation.
Tasmanian voters tend to vote below the line in higher numbers than the rest of the country, with Senator Abetz asking voters to pick him above his colleagues.
But that trend also works against him.
"It is a bit of a Tasmanian convention, this sort of voting, to put Eric Abetz last," Dr Bonham said.
"In the last election, he got nine times more last place votes than anybody else."
Outside chances
The ACT also likes to vote below the line, but there is only two spots up for grabs.
Labor's Katy Gallagher will safely be re-elected, but Liberal Senator Zed Seselja is a target of the Greens and independents including, high-profile former Wallabies' captain David Pocock.
"There has been this sort of thing that the ACT Senate seat might fall for a long time, it has been talked about various elections in various forms and never happened," Dr Bonham said.
"If Pocock gets a high enough vote to get over the Greens into third place, then he could, in theory, get a cascade of preferences from everywhere and beat the Liberals."
However, Dr Bonham said, Pocock was as likely to win a spot in the Senate as the Wallabies are to beat the All Blacks — i.e., not very.
