Dr Rowan William's repeated the Church of England's opposition to assisted dying as Lord Joffe, the peer behind an expected Bill to make assisted suicide legal for the terminally ill, indicated that he might drop the most contentious part. Peers discuss euthanasia today.
In a moving interview, Dr Williams describes how he sat by the bedside of his mother, Nancy, during her final months of dementia.
But despite this experience, he is still against assisted dying "chiefly on the grounds of my religious commitments - the conviction that life is a gift from God that we cannot treat as a possession of our own to keep or throw away as we choose," he said.
Dr Williams, writing in The Mail on Sunday, says: "I sat by my mother in her last painful months of decline and dementia. I should be the last person to understate what this feels like, or to deny that in such circumstances you can find yourself wishing desperately for it all to be over.
"But I don't know now how much this had to do with my own distress and feeling of helplessness."
Lord Joffe said that the House of Lords Bill aimed at legalising euthanasia may be watered down in a bid to win more support.
He might amend his Bill so that doctors could only help dying patients indirectly by prescribing lethal drugs, rather than administering the medicine themselves, he said.
The move could help the Bill win the support of the medical community and other influential MPs and peers.
Earlier this year, the British Medical Association dropped its historic opposition to euthanasia when its members voted to adopt a neutral stance on the issue.
The Government has said that it too has a neutral stance and will listen to the debate as well as giving MPs and peers a free vote on any Bill to come before them.
Lord Joffe's Bill ran out of parliamentary time when he introduced it last year, but prompted a Lords select committee to review the law on assisted dying. The committee's report is due to be debated by the House of Lords today.
Lord Joffe plans to reintroduce his private members Bill early next month, and the Government has indicated that it could be given parliamentary time.