A majority of MPs have not announced their position on the bill, but those who have spoken have are divided by ethics and practical concerns.
Conservative MP Kit Malthouse, who is co-sponsoring the bill, told the BBC’s World Tonight he felt a lot of the concerns raised by other MPs had been addressed by the bill’s safeguards, but called the status quo a “horror show”.
Lib Dem leader Sir Ed Davey said he plans to vote against the bill, fearing it could make people “less free” rather than expand rights for the terminally ill.
“The real problem is people who are terminally ill could feel under real pressure psychologically at the end of their life,” Sir Ed said.
The government should instead focus on improving palliative care to ensure less painful deaths, Sir Ed said, adding: “I think it would change the debate for some people”.
Dr Gordon Macdonald, chief executive of Care Not Killing, which is campaigning against the bill, said: “The safest law is the one we currently have.
“This bill is being rushed with indecent haste and ignores the deep-seated problems in the UK’s broken and patchy palliative care system,” he added.
Conservative MP Danny Kruger told the BBC that, despite the efforts that have been made to add safeguards to the bill, he was concerned that in practice judges and doctors would end up “rubber-stamping” decisions.
He said he agreed with Leadbeater that “the status quo is not OK”, but felt it was palliative care that should be overhauled.
“Due to innovations in medicine, pain relief and treatment… it should not be necessary for anybody to die in unbearable, physical agony any more,” he said.
Health Secretary Wes Streeting, who has said he will vote against the bill, has raised similar concerns, saying end-of-life care is currently not good enough to give people a real choice.
In response, Leadbeater said: “This is not about either improving palliative care or giving people the choice at the end of life that I believe they deserve.
“We have to do both, and they have to run in parallel.”