So when ads started appearing in Daniel Andrews' local suburban newspaper recently - accusing the Premier of trying to legalise "patient killing" - few were surprised that the pro-life group was involved.

At its head is seasoned campaigner Margaret Tighe, now in her 80s, and a veteran of decades of "punishment politics". From the battle to decriminalise abortion, to the IVF debate, her organisation has routinely targeted MPs in volatile seats with highly emotive scare campaigns.

The assisted dying bill in Victoria - endorsed by Andrews himself - has brought Tighe out again to wage moral war.

"We're taking the fight right up to the enemy," she told Fairfax Media this week as her group distributed leaflets across eight marginal seats - as well as Andrews' Mulgrave electorate. "It's a controversial issue, so it's important that people know what's being proposed."

With state parliament set to decide whether terminally ill people should have the right to a physician-assisted death, Right to Life is part of a formidable coalition of opponents: from religious leaders and medical specialists, to disability groups and hardline campaigners, all fighting the legislation.

Politicians are being bombarded with pro forma emails and letters - some scripted by church volunteers, others by national anti-euthanasia agencies - urging them to vote against the bill when it is introduced at Spring Street later this month.

Delegations of faith-based representatives and doctors are criss-crossing the state to meet MPs: a few weeks ago, for instance, Australian Christian Lobby state president Dan Flynn brought in three doctors to see upper house leader Gavin Jennings, the Premier's right-hand-man in cabinet, to argue the need for better palliative care.

"The best arguments are not necessarily religious," says Flynn.

And Right to Life recently paid for US anti-euthanasia campaigner William Toffler, a controversial Catholic doctor who believes abortion can lead to breast cancer, to conduct a speaking tour around Australia.

But the biggest combatant of all is the Catholic Church. On Thursday, as Melbourne shivered through another frosty winter morning, Pat Shea, a parish volunteer from Inverloch, entered the electorate office of Bass MP Brian Paynter, holding a petition and letters from churchgoers with a simple message: don't vote for the bill.

The seeds of that message were on sown on April 18, when Archbishop Denis Hart wrote to priests asking them to "pray and to act", in other words, to get mobilised and to find "lay people" to spread the church's concerns about the renewed push for reform.

Attached to his letter was a two-page document co-signed by his bishops, arguing voluntary euthanasia was "never justified" and merely represented "the abandonment of the sick and the suffering". The Catholic Education Office passed that document on to its Victorian schools. Some are now getting politically active.

"The case for legalised 'Physician Assisted Suicide' is a direct attack upon our Catholic beliefs and would further erode society's respect for the 5th commandment," said one recent newsletter to parents at St Joseph's School in Wonthaggi.

"Euphemisms, such as 'assisted dying' and 'dying with dignity' are being hailed as acts of compassion, yet, with the sugar coating removed, euthanasia is about actively killing someone, and assisted suicide is helping someone to suicide. We need your help to convince our local member of parliament to oppose 'Physician Assisted Suicide' and to promote Palliative Care. An information session is planned."

Opinion polls show the church is fighting an uphill battle, with up to 85 per cent of the community in favour giving of terminally ill people the right to a physician-assisted death.

If the legislation succeeds, it will be the first time such a law has passed in Australia since euthanasia was legalised in the Northern Territory in 1995, only to be overturned by the federal parliament one year after taking effect.

The difference for Victoria is that the Commonwealth has no power to repeal the state euthanasia legislation. And in a sign of just how tight the numbers are likely to be, government insiders have not ruled out introducing the bill in the upper house, where some are more confident of securing a majority when the legislation is put to a conscience vote.

This unusual tactic would give more time to undecided MPs in the lower house, where Andrews and Health Minister Jill Hennessy will champion the bill, but Deputy Premier James Merlino, Opposition leader Matthew Guy, and a considerable number of Liberal, National and Labor politicians are set to vote against it.

Most, however, are hopeful the debate won't be quite as vicious as the battle to decriminalise abortion in Victoria in 2008. Back then, animal organs were sent to cabinet minister Jacinta Allan; plastic fetuses were distributed to pro-choice politicians accusing them of being murderers; some MPs were even sent abusive emails directly to their Blackberries from angry members of the public as they sat down from speaking during the vote.

"I think inside the chamber it will be a pretty respectful debate, but outside the chamber - who knows?" says Greens MP Colleen Hartland.

Hartland recalls the abortion debate well, partly because it happened the same year she introduced her own private members' bill for voluntary euthanasia, which was resoundingly defeated. But a lot has changed since then: the influence of religion; the views of MPs; the public's momentum.

The "Yes" side of the campaign is spearheaded by neurosurgeon Brian Owler, who headed the government's expert panel for the bill, Dying With Dignity's Dr Rodney Syme, and newcomers like Go Gentle, the not-for-profit body set up last year by TV personality-turned-euthanasia advocate Andrew Denton.

Denton has devoted the past few years to reforming the law, but was forced to withdraw this week to have multiple bypass surgery after being diagnosed with advanced heart disease.

Until he can return, Go Gentle's work will continue under its campaign manager Paul Price, a former senior adviser in the Baillieu Liberal government. In a bid to mobilise the "silent majority", a new ad will soon be released in marginal seats asking people whether the individual, or the church, should have the right to choose how long they suffer in intolerable pain before death.

The aim, says Price, is to overcome the "noisy minority of mostly faith-based opponents".

"They are organised and active," he says.

Indeed, Right to Life stepped up its campaign in May, when Tighe sent a letter to every parliamentarian with a table of the nine MPs in marginal seats that her group targeted over abortion a decade ago - plus the swings against them at the 2010 Victorian election. It was hardly a subtle threat.

Others, like the ACL's Dan Flynn or Paul Russell, from the national anti-euthanasia group, HOPE, have mobilised their supporters to take part in a grassroots letter-writing campaign, while representatives travel from electorate-to-electorate in the hope of swaying MPs.

The state's Christian leaders have also made it clear that the battlelines have been drawn: note, for example, this week's "open letter" in the Herald Sun, signed by leaders in the Greek Orthodox, Lutheran, Anglican, Catholic, the Syro-Malabar Eparchy, Ukrainian Catholic, and Coptic Orthodox Churches.

Andrews, the Catholic premier whose resistance to voluntary euthanasia shifted last year after the death of his father, responds like this: "People are free to express their views," he says.

"I would hope, though, that this debate is conducted in the spirit of respect. My own conscience tells me that this is the change that needs to be made."