Ministers say the scheme will allow the NHS to continue to attract medical staff after the UK has left the EU.
Yet Labour accused the Tories of "tying themselves in knots" and using "dog whistle anti-immigrant rhetoric" while still trying to attract foreign workers to keep public services ticking over.
Labour's drive on Friday will focus on supporting women in the workplace, introducing measures to raise statutory maternity pay.
The Conservatives' pitch on a new NHS visa will form part of the party's points-based immigration system which it plans to introduce after Brexit.
The move is part of a drive to tackle the concern the NHS will struggle to attract the staff it needs when the UK leaves the EU. There are currently 100,000 vacant jobs already in the public health service.
Under the scheme, the visa cost of health professionals would be halved from £928 to £464, while applicants would be guaranteed a decision within two weeks.
Applicants coming to work in the NHS would receive preferential treatment with extra points under the points-based system, and no cap on numbers entering through the NHS route.
They would also be able to pay back the cost of the immigration health surcharge through their salary if the charge is not already covered by the NHS trust offering the job.
The Tories have already announced a fast-track visa route to attract specialists in science, engineering and technology.
The Royal College of Nursing (RCN) was critical of the Conservatives' plan, saying "more ambitious plans" were needed to fill job vacancies in the NHS.
Dame Donna Kinnair, chief executive and general secretary of the RCN, said: “Failure to train enough nurses is leaving NHS and social care short-staffed and forced us to recruit overseas in the short-term.
“A fairer immigration system is a key demand we’re making of politicians this election – valuing skills and not fixating on arbitrary targets – but the devil will be in the detail and we cannot be satisfied by rhetoric alone. The NHS doesn’t operate in isolation and nurses work in social care and many other places.
“But it is of deep regret that the prime minister is preserving the immoral and heartless charge for overseas nurses to use the same services they keep running. It should be abolished, not spread out every month.
"There are tens of thousands of unfilled nursing jobs and we need more ambitious plans than this to address it.”
Mr Johnson promised to "look into" the criticisms raised by the Royal College of Nursing during a visit to King's Mill Hospital in Derbyshire.
The Prime Minister insisted it is “pure Loch Ness Monster” territory to suggest the NHS would be up for grabs under his Brexit deal.
Home secretary Priti Patel said the introduction of an Australian-style points-based immigration system would allow the country to control its borders while still allowing in the expertise it needs.
She said: "That means the best of both worlds – attracting talent from around the world so our NHS continues to provide brilliant service while ensuring that it isn’t put under strain by opening Britain’s borders to the entire world."
However shadow home secretary Diane Abbott rubbished the proposals, saying: “They use dog whistle anti-migrant rhetoric but are forced to accept we need migrant workers for key sectors, not just the NHS, but many more besides."
Liberal Democrat home affairs spokeswoman Christine Jardine said the visa fees amounted to a “nurse tax” on staff from the EU who could currently come to Britain for free.
“The Conservatives have effectively created a new nurse tax. It is an insult to the thousands of people who dedicate their lives coming to work for our health service from the EU,” she said.
Shadow attorney general Shami Chakrabarti was critical of the Conservatives' visa plan, saying: "I think that the Conservatives speak with forked tongue so they're going to make this offer to doctors and perhaps to senior nurses because a lot of nurses don't get paid enough to be valued by the Tory party's immigration policy
"What about people who work in social care? We have a social care crisis in this country and we need people to come and work in that sector as well.
"I think the real problem is Boris Johnson's conservative party have been playing dog whistle politics on immigration."
She added: "The NHS is a massive problem for them and for the country and we need people from around the world to come and contribute as my parents once did, as Diane Abbott's parents once did and we're never going to forget that."
Labour propose 'workplace revolution' for women workers
The Labour Party will focus on trying to bring about a "step change" in the way women are treated at work.
Among the proposals include:
- Increasing statutory maternity pay from nine months to 12 months
- Improve entitlement to flexible working hours
- Take further steps to tackle sexual harassment at workplaces
Shadow women and equalities minister Dawn Butler said: “Labour will deliver a workplace revolution to bring about a step-change in how women are treated at work.”
However the Conservative Party criticised Labour's plans, saying it would result in job losses.
Difficult start to campaign for both parties
Labour and the Conservatives have endured a tricky start to the campaign, with candidates from both parties stepping down due to controversies.
Ex-BBC Radio Norfolk presenter Nick Conrad quit as a Conservative Party candidate after facing criticism for comments he made on a rape case in 2014, saying women should “keep your knickers on”.
Labour’s candidate for Aberdeen Kate Ramsden stood down over a social media post – highlighted by The Jewish Chronicle – likening Israel to “an abused child who becomes an abusive adult”.
She apologised unreservedly saying she could see that “many Jewish people had been hurt by my words”.
A Labour source said the party had taken “swift and robust action” after extra due diligence checks had uncovered material of concern.
Labour’s candidate for Edinburgh South, Frances Hoole, was also dropped after the party refused to endorse her following a social media attack on her SNP opponent, Joanna Cherry.