Collocations for obstacle - noun

big, chief, main, major | enormous, formidable, serious
The attitude of the unions is a serious obstacle.

impossible, insuperable, insurmountable
Lack of money has proved an almost insurmountable obstacle.

pose, prove, remain | come across, encounter | overcome, remove, surmount
He was determined to overcome all obstacles in his way.

~ for
Lack of childcare provision can be a major obstacle for women wishing to work.

~ to
The huge distances involved have proved an obstacle to communication between villages.

an obstacle in the path/way (of sb/sth)
The release of prisoners remains an obstacle in the path of a peace agreement.