Background Spain currently lacks a competency framework for palliative care nursing. Having such a framework would help to advance this field in academic, governmental, and health management contexts. In a previous phase of research, 98 proposed competencies were presented to a sample of palliative care nurses. They accepted 62 of them and rejected 36. Methods In the present phase, we conducted a qualitative exploratory study using consensus techniques with two modified nominal groups to gain an understanding of why the 36 competencies had been rejected. Twenty nurses from different areas of palliative care (direct care, teaching, management, research) participated. We conducted a thematic analysis using NVivo12 to identify meaning units and group them into larger thematic categories. Results Participants attributed the lack of consensus on the 36 competencies to four main reasons: the rejection of standardised nursing language, the context in which nurses carry out palliative care and other factors that are external to the care itself, the degree of specificity of the proposed competency (too little or too great), and the complexity of nursing care related to the end of life and/or death. Conclusions Based on the results, we propose reparative actions, such as reformulating the competencies expressed in nursing terminology to describe them as specific behaviours and insisting on the participation of nurses in developing institutional policies and strategies so that competencies related to development, leadership and professional commitment can be implemented. It is essential ​​to promote greater consensus on the definition and levels of nursing intervention according to criteria of complexity and to advocate for adequate training, regulation, and accreditation of PC expert practice. Locally, understanding why the 36 competencies were rejected can help Spanish palliative care nurses reach a shared competency framework. More broadly, our consensus methodology and our findings regarding the causes for rejection may be useful to other countries that are in the process of formalising or reviewing their palliative care nursing model.