A majority of the public in England support junior doctors' strike action so long as they provide emergency care, an Ipsos MORI poll commissioned by BBC Newsnight suggests.
Overall 66% of respondents said they support the strike, and 16% oppose it.
But support drops to 44% if emergency care is not provided.
The poll comes on the eve of a strike by junior doctors, who will provide emergency care only for 24 hours from 08:00 GMT on Tuesday.
A further strike over is planned for Tuesday 26 January, in which emergency care will again be staffed.
A full walk-out - with junior doctors providing no emergency cover - is set for Wednesday 10 February.
The Newsnight poll, commissioned jointly with Health Service Journal, was of 869 adults in England.
If emergency care is not provided, support dips significantly - 44% said they would support a strike, compared to 39% who then said they would oppose it.
Junior doctors are striking over the prospect of a new contract in England. Scotland and Wales have both said they will be sticking to their existing contracts, while Northern Ireland has yet to make a decision.
Prime Minister David Cameron on Monday called on medics "at the late stage" to get back around the table before the proposed walkout.
"This strike is not necessary, it will be damaging," he said.
NHS England estimates nearly 4,000 operations and procedures out of 31,000 will be cancelled because of the strike.
It says everything possible is being done to provide safe emergency care and minimise the impact on patients.
Only 8% of those polled said junior doctors are striking over their contract.
More than 60% said junior doctors are taking this action because of working conditions - such as long hours - or over pay. Eight per cent cited "politics" as a reason for the strike.
More on this story on BBC Newsnight on Monday 11 January at 22:30 GMT on BBC Two and afterwards on iPlayer