As Ms Hickey defended her vote against the government's mandatory sentences for serious child-sex offenders, Labor leader Rebecca White said it was clear Tasmania now had a minority government and Premier Will Hodgman should resign.

Mr Rundle said Mr Hodgman had "turbo charged" the economy and Ms Hickey was "irredeemable".

"She should be condemned. It was opportunistic and totally disloyal," Mr Rundle said.

"It is hard to see how she can be pre-selected and she will probably jump ship and go to Labor.

"This government has turbo-charged the economy. Will Hodgman has done that and Hickey is distracting from a very good government.

"I don't think anyone can sort Sue Hickey out - she is irredeemable.

"If she thinks her rebel status will help her it didn't help Bob Cheek - he lost his seat."

Ms Hickey defended her vote and said lawyers and the Sentencing Advisory Council had recommended against mandatory sentencing for sex offenders.

"It was an awful position to be in," she said on Thursday after casting the deciding vote in Parliament on Wednesday night.

"I want to achieve the best I can in the next three years and I am doing everything I can to do that with my sense of honour in tact.

"If the Liberals don't endorse me I will deal with that, but I support Will Hodgman I am just a liberal Liberal.

"Mandatory sentencing undermines the separation of powers that ensures the independence of the legal system.

"Parliament should never make laws based on popular opinion...it should only be on informed advice.

"It would have been much easier for me to have supported a 'populist policy' but it is braver and more true to my conscience to not support this bill in its current form."

Ms White wants Mr Hodgman to resign.

"What we saw on Wednesday night in the Parliament was the government lose another vote," Ms White said.

"Will Hodgman made repeated claims before the last state election that he would not govern in minority. If he is true to his work then the only option for the Premier is for him to resign.

"What the Premier needs to tell Tasmania is if he is a man of his word or not.

"If he is continuing on in the role, then I think all Tasmanians can take from that is he told them a lie before the last state election."

Mr Hodgman said the government would continue to "pursue our policy to ensure there is guaranteed jail time for serious child sex offenders".

"It is a policy developed in close consultation with victim groups and survivors of sexual abuse and one which we have taken to two elections, receiving incredibly strong support from the community," he said.

"Labor has now voted against mandatory sentences for child sex offenders three times and it proves once and for all that they are soft on crime and have refused to listen to the victims.

"It also proves that their con job earlier this week about wanting to be tough on crime was a total fraud - because of their actions serious child sex offenders can still avoid jail entirely."

Election analyst Dr Kevin Bonham said the government's future with Ms Hickey was uncertain.

"We have a majority government but it is not always able to deliver and that is not a very pleasant situation for the government to be in," he said.

"It's still a majority government technically but it has a kind of persistent case of backbench rebellion - they have to put up with it to keep going.

"She is unlikely to get endorsed because a lot of people (in the Liberal Party) will be very angry and will argue you can't reward disloyalty.

"It is hard to say how relations between her and the government will pan out.

"She could become an Independent and put Labor into government mid-term but they would have the prospects of being belted at the election if they did that.

"If she became an Independent they would be in minority and Will Hodgman vowed not to govern in minority. She would be able to bring the government down any time then as an Independent."

Political analyst Professor Richard Herr said the government was not in minority because of Ms Hickey's vote against Liberal policy.

"She is still a member of the Liberal Party and still votes mostly for their policies," he said.

"It does mean there is a degree of unpredictability for the government."

Survivor and Beyond Abuse founder Steve Fisher said survivors were "in shock" after the vote in Parliament on Wednesday night.

"We're very surprised and disappointed," Mr Fisher said.

"Sue Hickey is basically running the Parliament, it's crazy.

"We need mandatory sentencing because otherwise people will not come forward if they know the perpetrator will not have to pay for what they have done."

Some political observers who did not want to be named, said the government was in "chaos" and Ms Hickey was "creating havoc".

"If she had just shut up she would be a Minister by now," one former MP said.

Former Liberal leader Bob Cheek said while he liked Ms Hickey she was a "turncoat".

"Will is doing a good job and she was put there by Labor and the Greens," he said.

"We are chalk and cheese. She has no agenda but has to vote with them occasionally to thank them for the Speaker's job.

"Sometimes people succumb to the power and publicity. It all goes to your head and you are seduced by power."

Australian Lawyers Alliance Tasmania president Fabiano Cangelosi said he was pleased the bill was defeated because there was no evidence mandatory sentencing worked.

"It doesn't work because crime is more complex than simply putting up a penalty, " Mr Cangelosi said.

"Causes of crime are more complex than that, a more nuanced response is required. All the evidence from around the world tells us that.

"It is pleasing to see that Ms Hickey has the courage of her convictions."