If you support a different candidate afterwards can you switch candidates?
It's like an actual election, if your vote is cast you cannot change it anymore.
I mean like once the primaries are over and your candidate doesn't win does it go away?
You can always remove the banner in your Forum Profile.
Just click on "Forum Profile Information", scroll down to the boxes and deselect "show endorsements in my posts".
After the primaries, there will of course also be a general election mock election with new avatars to choose.