The Prime Minister has been accused of disrespecting nurses by turning down an invitation to speak to their annual conference.
Theresa May was asked to speak at the Royal College of Nursing event in Liverpool, but declined, and the Conservative Party did not send a speaker in her place.
Labour leader Jeremy Corbyn and Liberal Democrat leader Tim Farron both addressed the conference on Monday.
RCN general secretary Janet Davies has written to the Prime Minister's office, saying that the conference was "extremely dissatisfied" with her response.
She wrote: "Our members are disappointed and saddened, and feel disrespected by the Prime Minister. Nurses were keen to hear from the Prime Minister personally about her plans to alleviate the difficult, and sometimes impossible situation, in which they are working.
"Whilst we are pleased the Prime Minister states that she recognises the value of nursing, this does not reassure us, and feels like empty platitudes when we see no real action being taken to improve the lives of both patients and nurses.
"This week, our members have spoken passionately about their own personal experiences, working both with insufficient resources to do their job safely and effectively, and insufficient resources to live their lives well, pay their bills and care for their families, or even travel to work to do the job they love so much."
Ms Davies pointed out that RCN members had taken the "unprecedented" step of backing a summer of protests over the government cap on their pay, adding: "Many never thought it would come to this and are now looking for guarantees that this Government will listen and act on the voice of nurses who keep our NHS going in the most difficult times."
Delegates at the conference gave a huge round of applause to Ms Davies when she read out the letter today.
The RCN, which has 270,000 members, has warned that low levels of pay are responsible for tens of thousands of unfilled posts.