shift one's ground
verb1
To change one's opinion in a way that contradicts what one has previously held.
- Since then, and after high-level in-person talks between ScotRail and TSSA General Secretary Maryam Eslamdoust, "the company has done nothing to suggest they are prepared to shift their ground", the union said.2024 April 3, “Network News: Fresh manager strikes at ScotRail”, in RAIL, number 1006, page 9: