chief difficulty
noun phraseUK /tʃiːf ˈdɪfɪkəlti/
US /tʃiːf ˈdɪfɪkəlti/
The biggest problem that makes something hard to do.
The chief difficulty in learning to ride a bike is keeping your balance.
OTHER MEANINGS
2. The most important thing that stands in the way of finishing a task.
Our chief difficulty was finding enough time to practice.
3. The hardest part of a job or plan.
The chief difficulty of the project was the tight deadline.
4. The main reason something is not easy.
The chief difficulty with the plan is that it costs too much.