In three weeks’ time, politicians will get their first look at Margo MacDonald’s private member’s bill to legalise assisted suicide in Scotland. Details of the proposed legislation are being kept under wraps, but the independent MSP has won cross-party backing for her right-to-die bill to be debated in parliament, ushering in the possibility that it could become law as early as next spring.

MacDonald, who has Parkinson’s disease and has already stated her wish to be allowed to choose to end her own life, secured 21 signatories to enable her draft bill to go forward. But so far none of the main political parties at Holyrood has offered support.

The issue of assisted suicide is a political hot potato. MSPs tread cautiously around such an emotive subject, appearing to believe that openly supporting the right of terminally ill patients to take their own lives is a vote loser.

But as the opinion poll in today’s Sunday Times shows, they are wrong. Asked if they supported MacDonald’s proposed change in the law to allow people with chronic illnesses who want to die to end their lives, 68% of respondents said yes. Just 8% said no and 24% said they didn’t know.

Asked whether people in Scotland have the same assurances as those in England that relatives can help loved ones with terminal, progressive or irreversible illness such as cancer or MS to die with less fear of prosecution, 69% said yes, 11% said no and 21% didn’t know.

The results are in line with previous polls on the same subject. A Populus survey in July for The Times found that three quarters of those polled wanted doctors to be allowed to help terminally ill patients to end their lives. Support was particularly strong among those aged between 55 and 64.

A YouGov poll for The Sunday Times at the end of last year revealed that public opinion had moved decisively in favour of assisted suicide, with most of those asked stating that they would consider euthanasia for themselves and believe that relatives who played a role in assisted suicide at clinics such as Dignitas in Switzerland should not be prosecuted.

MacDonald is pleased but not surprised by the results of today’s poll. She has already received support from Libby Wilson, the former doctor from Glasgow who has become the first person to be arrested under the new guidelines introduced by Keir Starmer, the director of public prosecutions in England, in an attempt to clarify the law on assisted dying south of the border. “I think Margo’s bill is a very good step in the right direction and will make a huge difference to a lot of people,” said Wilson.

In June, multiple sclerosis sufferer Debbie Purdy won a long battle to clarify England’s law on assisted suicide.

As MacDonald is only too aware, it is not the public who will determine the outcome of her private member’s bill. MSPs will vote on the issue and not all of them are guaranteed a free vote. This year, MacDonald wrote to the party leaders asking if they would give their MSPs a free vote on assisted suicide. The Scottish Conservatives and Liberal Democrats said they would, Labour said they were still thinking about it and the SNP said a decision would be taken after the wording of the bill was finalised.

MacDonald says that a covert campaign has been mounted against assisted suicide. “It has meant that some politicians are running scared rather than being guided by their own conscience,” she said.

Among those who oppose assisted suicide is the Catholic church, and it is using its influence to raise the issue in the Glasgow North East by-election taking place on Thursday.

Two of the candidates vying to replace the former speaker of the House of Commons, Michael Martin, in a constituency believed to be one of the poorest in Britain, are Catholic. David Kerr, the SNP hopeful, is a member of the conservative Catholic group Opus Dei, which follows a strict Vatican line on such issues.

Willie Bain, standing for the Labour party, is also Catholic but seems to hold more liberal views. Both men have been urged to state their views on assisted suicide by the Scottish Catholic Observer.

“I support the sanctity of life and I’m very opposed to Margo MacDonald’s End of Life choices bill,” Bain told the newspaper.

Kerr, a former BBC journalist, said: “I believe that if a patient is in pain then we kill the pain and not the patient.”

Traditionally, political parties have stayed out of moral debates such as assisted suicide. “It has always been an issue of conscience with leaders of all main parties not wanting to set out an official position, but rather leaving it up to individuals,” said James Harris, head of campaigns for the pressure group Dignity in Death, which supports the legalisation of assisted suicide.

Terry Sanderson, president of the National Secular Society, accused politicians of running scared from moral issues because of the influence of church leaders and urged them to start voting in line with public opinion.

“They have this old-fashioned idea that churches can corral voters to vote in the way they are told by their priests, but they can’t do that any more,” he said.

“The church is out of step with the electorate. Politicians have really got to grasp this nettle and see that a huge swathe of the country want this legislation and it shouldn’t be thwarted by the bleatings of a few church people.”

While the Catholic church in Scotland said the poll raised important questions about end-of-life issues, it added that MacDonald’s bill could open the way for the abuse of vulnerable people.

“The law is also about protecting the weak and vulnerable and we need to ask whether we are introducing a very dangerous framework for people who are at risk of abuse.

“It would be very easy for a person who thinks a relative is a burden or a drain on their inheritance to make use of the facility that is being set up.”

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