Brexit would give the NHS a multi-billion pound boost, London mayor Boris Johnson will insist as he kicks off a series of rallies on the first day of the official referendum campaign.
The Vote Leave organisation, backed by Mr Johnson and Cabinet heavyweight Michael Gove, moved the health service centre stage in the campaign as it claimed a large chunk of the the UK's £10.6 billion net contribution to Brussels could be diverted to hospital beds.
Mr Johnson is to spearhead a "Brexit blitz" of speeches across the UK with an address in Manchester, ahead of weekend events in Leeds and Newcastle.
Vote Leave's decision to highlight projected funding problems with the NHS is bound to heighten tensions within the Tory party as Prime Minister David Cameron has strongly defended his record on the health service.
The campaign group points to predictions showing the NHS could face a shortfall in funding of £12.3 billion by 2020-2021 as reason to divert resources to medical care.
"The UK's net contribution to the EU is £10.6 billion. This suggests the NHS deficit could nearly be eliminated if we Vote Leave and we choose to spend our money on our priorities like the NHS," a Vote Leave spokesman said.
Vote Leave chairwoman Gisela Stuart, a Labour MP, insisted money needed to be switched from Brussels to the NHS.
"The NHS is facing a crisis due to growing demand for healthcare and a squeeze on funding. This means that patients are not always getting the treatment that they need, when they need it.
"If we vote leave we will be able to stop handing over £350 million a week to Brussels and we will be able to instead spend our money on our priorities like the NHS. This will improve patient care.
"If we vote leave the money we send to the EU will plug some of the gaps in the NHS funding crisis - that's why leaving is the safer choice in this referendum," Ms Stuart said.
Justice Secretary Mr Gove is expected to echo the NHS warnings during a speech in Nottingham, as fellow leading Leave campaigners, Commons Leader Chris Grayling, and Northern Ireland Secretary Theresa Villiers, also step-up the Brexit campaign in the coming days.
Mr Johnson's rallying cry speech comes on the first official day of the campaign which sees rules governing spending and other areas come into play ahead of the June 23 vote.