Social care bosses and charities are backing a compulsory levy of as much as £20,000 to pay for elderly social care and they want ministers to clarify their position.
Mr Burnham accused the Conservatives of using the complicated issue of care reform to frighten voters as he insisted a flat rate inheritance levy was not on the agenda.
But he was careful not to rule out any options and would only say that further details would be set out before the general election.
The Conservatives are against the plan, which has been dubbed a “death tax”.
John Jackson of the Association of Directors of Adult Social Services, which represents social service bosses working for councils, backed the idea and said the extra funding as much needed.
Counsel and Care’s Stephen Burke added that radical reform and proper funding was needed to bridge the care funding gap, but he rejected the idea of a voluntary scheme, which is another idea under consideration.
“The problem with any voluntary insurance is that people will not think they need it and so will not take it up,” he said.
“Without getting enough people signing up the idea stops being viable. If you have a compulsory scheme, you would ensure there is enough funding to run the service in the future.”
A spokeswoman from the Department of Health confirmed that a decision would be made soon and added: “It is premature to start second-guessing the blueprint we will shortly set out.”