[take] {one's} side

to support a particular person, group, or idea in a dispute or conflict

During the argument, I decided to take my friend's side because I believed in her perspective.
During the debate, the politician strategically took sides with the popular opinion to gain more support.
Even though it was a heated debate, most of the team members chose to take the manager's side in the decision-making process.
In the argument between her friends, Jane decided to take sides with Sarah, believing she was right.
In a family disagreement, it's common for siblings to take each other's side, fostering a sense of unity.