shift (one's) ground
To adopt a different viewpoint or opinion. I was shocked when Liz suddenly shifted her ground and started seeing things as I did.
shift one's ground
Fig. to change one's opinions or arguments, often without being challenged or opposed. At first Jack and I were on opposite sides, but he suddenly shifted ground and started agreeing with me. Jim has very fixed views. You won't find him shifting his ground.
shift your ground
say or write something that contradicts something you have previously written or said.shift your ˈground
(usually disapproving) change your opinion or position, especially during an argument or a discussion: He’s shifted his ground on many major policy issues. OPPOSITE: stand fast/firm