break ranks
US /breɪk ræŋks/
UK /breɪk ræŋks/

1.
党の方針に背く, 離反する
to fail to keep in line with the other members of a group or organization; to abandon a common cause or position
:
•
One senator decided to break ranks and vote against his party's bill.
ある上院議員は党の方針に背いて、党の法案に反対票を投じることを決めた。
•
It's difficult for employees to break ranks when management is so unified.
経営陣がこれほど一枚岩だと、従業員が反旗を翻すのは難しい。