an uphill battle

If you refer to something as an uphill struggle or an uphill battle, you mean that it requires a great deal of effort and determination, but it should be possible to achieve it.

touch a sore spot and touch a sore point

Fig. to refer to a sensitive matter that will upset someone. (Fig. on the notion of touching an injury and causing pain.) I seem to have touched a sore spot. I'm sorry. I didn't mean to upset you. When you talk to him, avoid talking about money. It's best not to touch a sore point if possible.