Former senator Jacqui Lambie has tried her hardest to keep up media appearances since she resigned 18 months ago.

The outspoken Tasmanian was elected as part of the Palmer United Party in 2014 but quit to become an independent later that year before starting her own party.

But Ms Lambie found herself an unexpected casualty of the citizenship furore, tearfully resigning after finding she was "not as bloody Australian as they come".

Tasmania has six sitting senators up for election: three from Labor, one Liberal, a National and a Green.

Tasmanian political analysts say Labor and the Liberal Party are likely to pick up two seats each, so there are two in play.

To snag a seat, Ms Lambie will be battling against a Greens senator who just scraped in last time and a Labor senator who defied the odds at the last election.

Where do Labor and the Liberals sit?

Tasmanian Labor has more to lose than the Liberals this time around, with three sitting senators up for election: Carol Brown, Catryna Bilyk and Lisa Singh.

The Liberals' only sitting senator up for election is Richard Colbeck, placed first on the party's ticket, followed by former Young Liberal president Claire Chandler and Hobart City alderman Tanya Denison.

Political analyst Kevin Bonham said both major parties were likely to secure two Senate seats, but neither was guaranteed a third.

"Based on the results of last election, Labor were closer to a third than the Liberals were, so that would seem to stand them in good stead given the current state of national polling," he said.

Senator Richard Colbeck, Hobart councillor Tanya Denison (L) and Tasmanian Young Liberals president Claire Chandler (R) will be running for the Senate for the Liberals. ( ABC News: Henry Zwartz )

If Labor were to get a third senator, below-the-line votes would determine whether the successful candidate was union boss John Short or popular senator Lisa Singh.

Senator Singh faces an uphill battle to be re-elected, after being dumped to fourth (after Mr Short) on Labor's ticket; the second time the senator — who is not aligned with state Labor's left or right factions — has been demoted.

Tasmania's penchant for below-the-line voting has helped Lisa Singh in the past. ( ABC News: Ellen Coulter )

That position means she would need to be elected through below-the-line voting.

Trained under the state's Hare-Clark system, Tasmanians aren't afraid of below-the-line voting.

At the last federal election, about 28 per cent of Tasmanian Senate votes were below the line, compared with the national average of 6.5 per cent.

Mr Bonham said while Senator Singh was elected in her own right at the 2016 double-dissolution election, it would be more difficult this time, with a larger quota needed in the half-Senate election.

Lisa Singh's battle at the 2016 election has inspired a book. ( ABC News: Ellen Coulter )

"This time to be a chance, she has to knock John Short out, short of a quota, and then start taking over getting the party votes that flow through to Labor," Mr Bonham said.

It's unclear if a grassroots "re-elect Lisa Singh" campaign will be run again, but a timely book release may help her chances.

The book, edited by former Labor senator Margaret Reynolds, details Senator Singh's 2016 win and is critical of the factional manoeuvring that meant it almost didn't happen.

Greens 'quite likely'

With two seats in play, who else has thrown their hat in the ring alongside Ms Lambie?

Nick McKim has had a rise in profile since the last election. ( ABC News: Emilie Gramenz )

Greens senator Nick McKim is campaigning hard, having narrowly scraped in ahead of One Nation in 2016.

His national profile has been given a boost since then, after he was made The Greens' immigration spokesman, and he has recently made local news coverage by calling for action on climate change in the face of wilderness fires.

Kevin Bonham said Senator McKim was "quite likely" to win a seat.

"The Greens' votes from last time translate to most of a Senate quota," he said.

"Even if it drops back a little bit it's difficult to see two parties getting over it. But the scenario in which he might be in trouble would be if Lambie and Labor both did very well."

Can Lambie make it back to the Senate?

Her campaign lacks funds, but Ms Lambie hasn't been shy of waving election placards and has gone so far as to put her mobile phone number out on social media for Tasmanians who want to stick a sign in their front yard.

Ms Lambie was in tears when she resigned in 2017. ( ABC News: Tim Morgan )

After her resignation, Ms Lambie was replaced in the Senate by Steve Martin, who later joined the Nationals and is now fighting to be elected in his own right.

Mr Bonham said it would be tough for the Nationals to hold onto the seat.

"Steve Martin's only been there for a short time [but has] tried his hardest to get lots of funding for the state," he said.

Another maverick from the north-west, fisherman Craig Garland, is giving it another shot after giving the major parties a fright at the Braddon by-election.

Mr Garland has some cult appeal, but Mr Bonham said for any of the minor party or independent candidates to have a chance, they would need Ms Lambie's vote to collapse.

Craig Garland enjoyed some support at the Braddon by-election. ( ABC News: Matt Roberts )

"It's a more crowded marketplace for that kind of politics at this election — you've got a lot of people who are going to be playing into this kind of populist, anti-party sentiment and we really don't know anything about how that's all going to split up," he said.

"So it is possible that the competition on that side of politics is going to result in none of them getting in.

"The other possibility is that one of them concentrates the vote enough that someone, probably Lambie, would get in."

Despite her high profile, Mr Bonham said Ms Lambie's work on the hustings might not be enough.

"I think that she's still high profile, and she's still seen around a lot, been touring the state and so on," he said.

"What this translates into votes … we don't know."

Given how tight the contest for the last Senate seats is expected to be, Tasmanians may have to wait a little longer than the night of May 18 for a final result.