Almost three-quarters of English people are in favour of an opt-out organ donor system, new research shows.
A survey by the British Heart Foundation (BHF) found that 74% of people are in favour of such a system - where people are registered as a potential donor unless they state otherwise.
The poll of 2,000 people in England comes ahead of a debate in the House of Commons on Friday on a new Bill which would introduce such a system in England.
The BHF is urging people to lobby their MPs ahead of the debate.
Its survey also found that among those who were not in favour of a change in the law, 42% said they were put off by concerns that they would not be able to opt out or would find it difficult to do so.
The charity said the proposed new system would allow any person opposed to donating their organs to opt out.
Its poll also showed that many members of the public underestimate how many people are on the organ transplant waiting list and how many people die while waiting for an organ.
NHS Blood and Transplant figures show that nearly 6,300 people are currently on the UK organ transplant waiting list.
And nearly 500 people died last year while on the waiting list, or being taken off the list after becoming too unwell for transplant.
The BHF said its poll also showed that many people are not aware of family members' wishes when it comes to organ donation.
6,296 people are on the organ transplant waiting list in the UK, including 148 children
Close to 24 million people are currently on the organ donor register
Last year, 470 people died while on the waiting list, or within a year of being taken off the waiting list after becoming too ill for transplant
Simon Gillespie, chief executive at the British Heart Foundation, said: "There is a desperate shortage of organs in the UK and introducing an opt-out system in England will better reflect the views of the general public and give hope to those currently waiting for a transplant they so desperately need.
"We are urging everyone to encourage their local MP to attend Parliament this Friday to debate a Bill that could save lives."
An opt-out system has been operating in Wales since December 2015, and in June last year the Scottish Government announced plans to move to a soft opt-out system.
Commenting on the poll, Sally Johnson, director of organ donation and transplantation for NHS Blood and Transplant, said: "Under the proposed system you would be a donor unless you don't want to donate.
"But if you support organ donation you don't need to wait. Tell your family now that you want to become a life-saving donor. People are dying every day in need of a donated organ."
The BHF has set up a web form to enable people to write to their MP to urge them to attend the debate, which can be found at: bhf.org.uk/organdonation