My department head/line manager has offered me a change in role within our wider discipline, covering areas and responsibilities that he believes my strengths lie in. It means losing some areas of focus that I currently enjoy with my current role, but gaining experience and knowledge (hopefully supported properly) in tangentially, but associated, pieces of work (which I previously had not really considered).
However, due to recent holidays and sick days on my part over the last couple of weeks, and travelling on his part, he initially was able to speak to me only via phone on Thursday, giving me the weekend to review a draft job specification of this new role. It's now Tuesday evening and I was told this afternoon I must give him an answer tomorrow.
There are also external factors which, despite being assured they're unrelated, can't be ignored: redundancies and people leaving from roles that did the sort of work I would be taking on in this 'new' job, even though taking a step back, it does fit with my skillset.
Am I within my right to ask for longer than three working days to decide about this, or should have including the weekend given me enough time? How long is appropriate to ask for, and how can I phrase this?