The union said a declining number of nursing degree courses and university closures risked creating an ‘irretrievable downward spiral' in workforce planning.
The NHS Long Term Workforce Plan published in June 2023 aims to grow the nursing workforce from around 350,000 nurses to around 550,000 in 2036/37.
However, in the last four years, the number of people starting nursing courses has declined at an average rate of 6.7%. If this trend continues, the RCN said the next two years would see the NHS in England 10,952 nursing students short of it target.
In order to meet the target, the RCN said applications must increase on average by 4,466 (11%) with the number of acceptances needing to rise on average by 2,330 (10.4%) every year.
However, student nursing applicants numbers have dropped significantly since the Government removed its bursary and ended funded tuition in 2017.
In addition, in a survey of over 500 nurse educators in England, six in ten (61%) said they were being directly affected by redundancy, a staffing restructure or recruitment freeze.
Patricia Marquis, executive director for RCN England, said: ‘The trends are deeply concerning and require swift and decisive action. The next government must fund tuition fees for nursing students, reintroduce universal maintenance support and stabilise the higher education sector.'
NHS Providers chief executive Sir Julian Hartley said: ‘The predicted shortfall in nurses would exacerbate existing pressures on the NHS, including long waiting times, delayed treatments and staff burnout.
‘The worrying decline in student nurse numbers and potential closure of nursing courses could also lead to a long-term negative impact on the NHS workforce, undermining trusts' efforts to recover from the pandemic and tackle care backlogs.
‘The next government must commit to nurturing the health and care workforce, including by fully funding the NHS Long Term Workforce Plan.'