The Royal College of Nursing’s leader will urge Rishi Sunak to “get this job finished” and enter negotiations to end strikes.
Pat Cullen will use a speech at the RCN’s annual congress in Brighton to say the Government will be forced to act if nurses give the union a fresh mandate for further industrial action.
A postal ballot on new strikes will open on May 23 and close on June 23.
The RCN has warned that strikes could go on until Christmas, which would force the cancellation of thousands of patient operations and appointments.
Ms Cullen will say the NHS and social care system are sailing “dangerously close to the wind” and “nurses are striking because our patients are dying”.
She will say: “In seven days from now, nursing staff in England will receive fresh ballot papers on the question of whether to continue with strike action for up to six more months.
“If you give the college another six-month mandate for strike action, across the whole of England’s NHS, then Government will be forced to act once more.
“Nobody wants to see twice as many nurses take strike action. Or twice as many hospitals affected by a strike.
“Prime Minister, you did the right thing to open negotiations with me in February. Before the 75th birthday of the NHS this July, let’s get this job finished.”
Ms Cullen will tell RCN members she has never “met a nurse or support worker who wanted to be on a picket line”.
She will add: “Standing outside our work became the only way to change what was happening inside.
“Patients are not dying because nurses are striking; nurses are striking because our patients are dying. It is as clear as that.
“The health and care system, across the whole of the UK, is sailing dangerously close to the wind right now.
“It is brutally unfair on your patients and the conditions feel intolerable for too many nurses and nursing support workers.
“Many people I spoke to on picket lines were in tears at how far they had been pushed and never thought striking would be a move nursing would ever make. Your courage and sheer determination has been an inspiration.
“Something fundamental has really shifted. Nursing has always had a voice. But this last year we decided to use it in a way that astounded everybody.
“After years of feeling left behind or unheard, patronised and misunderstood, undervalued and out of sight, we had a message for every single politician in this country: never again dare to believe that you can keep nursing staff quiet.”
Discussing new laws which will force unions to offer “minimum service levels” during strikes, Ms Cullen will say the Government has resorted to such measures after losing the “public debate” and “the confidence of our public sector and other key workers”.
She will ask: “What did they resort to? A new law to stop you taking strike action. A law to threaten you with the sack. It is draconian, unnecessary and vindictive.
“It might be in its final stage in Parliament, where we continue to help fight it and even winning some key votes to defeat Government, it is simply not worthy of being in the laws of this land.
“If it gets through, I will hold the Labour Party to their word on abolishing it.”
Ms Cullen will also say the way “this Government talks about migration sickens me”, adding: “Diversity is one of our many strengths as a profession. In this hall alone there will be colleagues who completed their education, and perhaps started their careers, in Africa, in Asia, in the Americas.
“Whether somebody comes to this country ready to work as a highly skilled nurse, or they arrive as a political refugee from war or persecution, or they simply want a new and prosperous life in the UK, they are beyond welcome.”
On Monday, Ms Cullen urged ministers to prevent nurses from “going into the winter months on strike action again”.
She had initially urged members to accept the Government’s revised pay offer of 5% for this year and a one-off payment for last year.
Asked about remarks by Energy Secretary Grant Shapps, who said her stance was “confusing”, Ms Cullen told BBC Radio 4’s Today programme: “No, it’s not confusing.
“Tens of thousands of my members voted to tell the Government their last offer was not good enough, that’s very clear.
“What was the offer? It was basically a consolidated 9% over a couple of years, and that’s a really important point. And we’re saying to Government, let’s negotiate further and add to it.”
On Monday, Downing Street said some nurses would already receive double-digit pay rises under the deal rejected by RCN members.
The Prime Minister’s official spokesman said: “If it is now correct that they are saying their position is that they wish for double digit pay rises over two years, I would gently point out (that) under the deal they voted against, those at the bottom of, or middle of, band five under Agenda for Change, so nurses, would receive 10.7% and 10.3% over two years.”
He added: “I think that illustrates this was a fair and generous offer. It’s the one that the RCN leadership recommended to its members, it was subsequently accepted by the majority of other unions via the NHS staff council.
“It’s important that all unions recognise this collective decision has been made, it should be respected.”