Television personality-turned-euthanasia advocate Andrew Denton has been forced to pull out of the campaign to legalise assisted dying in Victoria because he has been diagnosed with advanced heart disease.

The 57-year-old must now have a triple bypass within days, just as the Andrews Government prepares to introduce a historic bill to Parliament.

Denton is one of the directors of Go Gentle Australia, which he established last year to lobby for voluntary euthanasia around the country.

Andrew Denton believes most Australians support voluntary euthanasia. ( AAP: David Mariuz )

The organisation's campaign manager Paul Price insisted work to give terminally ill people the right to a doctor-assisted death would continue while Denton recovered from surgery.

"The Go Gentle campaign continues in full force," Mr Price said.

"In the next weeks and months we will be marshalling the support of the more than 75 per cent of Victorians who want voluntary assisted dying to become law."

Mr Price said Denton hoped to rejoin the debate in September.

Denton has put his career on hold in recent years to campaign for assisted suicide in Australia.

His push has been driven by a deeply personal experience watching his father Kit Denton die from heart failure in 1997, which he described as the "most profoundly shocking experience of my life".

Prime Minister Malcolm Turnbull sent his best wishes to Denton and his partner, journalist and presenter Jennifer Byrne.

"Lots of love, Andrew. A swift recovery, take care of yourself," he said.

"You are invincible, don't forget that, you'll be right. Take care, lots of love to you and Jen."

Christian leaders come together to oppose euthanasia laws

Debate about the vexed issue of voluntary euthanasia is intensifying in Victoria, where MPs are considering a model that would let people suffering from an advanced and incurable disease, illness or medical condition seek a doctor-assisted death from 2019.

If the proposed laws pass by a conscience vote later this year, Victoria could become the first state in the country to legalise voluntary euthanasia.

On Monday, seven Christian leaders including those from the Catholic, Anglican, Greek Orthodox and Lutheran churches published an open letter to Premier Daniel Andrews arguing against the proposed legislation.

"Euthanasia and assisted suicide represent the abandonment of those who are in greatest need of our care and support," they wrote.

Mr Andrews said he expected "robust debate" about the legislation, but he hoped it would be respectful.

"My own conscience tells me that this is the change that needs to be made," he said.