Alliance may use human rights and disability equality arguments.
A new anti-euthanasia coalition has created further divisions in the sector over assisted dying.
The Care Not Killing Alliance has been set up to counter the pro-euthanasia lobby as Parliament debates the Private Member's Assisted Dying for the Terminally Ill Bill.
But one member organisation hopes it will steer the anti-euthanasia camp away from religious arguments, despite the involvement of several faith groups.
"We want an alliance that actually puts arguments from a human rights and disability equality perspective, as opposed to the religious perspective," said Simone Aspis, parliamentary campaigns and development manager at the British Council of Disabled People.
Aspis says efforts to counter the proposed legislation, which would allow physicians to help patients who have fulfilled the necessary criteria to die, have previously been dominated by religious organisations. "We are hoping this will move beyond that," she added.
Dignity in Dying, one of the key organisations backing the Assisted Dying for the Terminally Ill Bill, is unmoved by the 18-strong alliance.
"This is the same name, the same faces and the same arguments," said Mark Slattery, head of communications at Dignity in Dying.
The charity feels no obligation to change its own approach, even though one alliance member is attempting to block its recent re-brand. The Association of Palliative Medicine and the Medical Ethics Alliance last month called on the Government to reject Dignity in Dying's trademark application.
The organisations claimed the new name was monopolising a common English phrase and investing it with a different meaning.
Meanwhile, both pro- and anti-euthanasia charities are showing rare agreement over another government initiative - a tick-box form allowing people the option of letting relatives make decisions about life-sustaining treatment if they are incapable of doing so themselves.
Some in the media have said the form might be "euthanasia by the back door", but the anti-euthanasia Association of Palliative Medicine disputes this view.
"That is a misrepresentation," said Dr John Wiles, the association's chair. "I think it's right that people should choose not to have unnecessary treatment, but that's not euthanasia."
The tick-box document is being produced as part of the 2004 Mental Capacity Act.
The Assisted Dying for the Terminally Ill Bill received its first reading in the Lords on 9 November 2005
It is a Private Member's Bill, like another of the same name, which was debated by Parliament over the course of 2004 and 2005
The current Bill is tipped to return for a second reading in May, but will be opposed by anti-euthanasia groups.