The government says an "accommodation" will be reached with Labour MPs opposed to a controversial bill which would allow animal-human embryos to be created for scientific research.
In the last few days, prominent members of the Catholic clergy have called for MPs to have a free vote on the bill.
ALAN JOHNSON, HEALTH SECRETARY
"For people out there suffering from Parkinson's disease and motor neurone disease, this is not a question of some issue about the procedure through the House of Commons. This is an issue about whether we can find the drugs that can cure their illnesses. So this is the heart of the matter."
THE MOST REVEREND PETER SMITH,
ROMAN CATHOLIC ARCHBISHOP OF CARDIFF
"This is a matter which is clearly affecting many MPs.
"I have written to the prime minister myself asking him that, in view of these very important issues which touch on the sacredness of human life, its meaning and purpose, would he please grant a free vote, because that is what is really required."
SHAUN WOODWARD, NORTHERN IRELAND SECRETARY
Mr Woodward said the bill was an important piece of government business which must be passed, but suggested a compromise was possible.
"I believe it is possible, if we listen to the arguments and we remove the misunderstandings, to find a way forward so the government can complete its business."
CARDINAL KEITH O'BRIEN, ROMAN CATHOLIC ARCHBISHOP
OF ST ANDREWS AND EDINBURGH
"It is difficult to imagine a single piece of legislation which more comprehensively attacks the sanctity and dignity of human life than this particular bill."
EVAN HARRIS, LIBERAL DEMOCRAT
Mr Harris, a member of the Commons Innovation, Universities, Science and Skills Select Committee, said it was right to conduct research that "might be used to treat people with terrible diseases".
CARDINAL CORMAC MURPHY-O'CONNOR
"Certainly, there are some aspects of this bill on which I believe there ought to be a free vote, because Catholics and others will want to vote according to their conscience."
STEPHEN POUND, LABOUR MP
Mr Pound has said he will not be voting for the measure.
"We seem to be moving into a sphere where we are actually taking on the role of the creation of life."
MEDICAL RESEARCH COUNCIL; ROYAL SOCIETY;
WELLCOME TRUST; ACADEMY OF MEDICAL SCIENCES
"This research has massive potential to provide treatments for serious debilitating disorders ranging from developmental abnormalities in young children, to stroke, cancer, HIV/Aids, diabetes and Parkinson's disease, as well as better and safer treatment for infertile couples."
ANGLICAN BISHOP OF DURHAM, RT REV TOM WRIGHT
"The irony is that this secular utopianism is based on a belief in an unstoppable human ability to make a better world, while at the same time it believes that we have the right to kill unborn children and surplus old people, and to play games with the humanity of those in between."
DENIS MACSHANE, FORMER LABOUR MINISTER
"MPs are also ethically challenged by decisions to go to war, to vote for
nuclear weapons, or on issues like ID cards or length of detention before
"I respect the Catholic and other religions, just as I respect CND and
Liberty, but if every difficult issue with ethical implications is a matter for
free votes, then democracy, Parliament, and the purpose of government becomes meaningless."
DR KIERAN BREEN, PARKINSON'S DISEASE SOCIETY
"It gives us a tool by which we can try to understand why nerve cells die in Parkinson's. It will allow us to generate nerve cells which have the exact same genetic material that comes from the people who have Parkinson's.
"By doing this we can understand why the nerve cells live and why the nerve cells die. And possibly then develop treatments and even a cure for the condition."
ANDREW COPSON, BRITISH HUMANIST ASSOCIATION
"The ethical focus of our discussions should be what's best for human welfare. The research this bill allows will help to cure, find cures for diseases and it will do so, at very little ethical cost.
"It should be endorsed and approved and go forward."