Idiom: an uphill task
When something is an uphill task or an uphill struggle, it’s a difficult thing to do. This is usually because of obstacles put in your way by other people.
When you face an uphill task, you feel that however hard you try, the task will not get any easier.
The company is facing an uphill task in its efforts to expand into China. The Chinese authorities refuse to allow it to start trading in the country.
This idiom has its origin in the field of warfare. When fighting land battles, being on the high ground gives forces an advantage because it’s harder for the opponent to charge uphill.