go over to
US /ɡoʊ ˈoʊvər tə/
UK /ɡoʊ ˈoʊvər tə/

1.
2.
to change allegiance or support from one side to another
:
•
Many voters decided to go over to the opposing party.
•
After the scandal, some supporters began to go over to their rivals.
to change allegiance or support from one side to another