could any American explain to a foreigner how much freedom do federal legislators have to ignore their party, even to vote against it?

https://linux.community/post/4058917

They have complete legal freedom to break with the party.

But if they go to far, they’ll find the party is funding their primary opponent instead of them.

Yeah, it’s easy to forget because of the power the parties have now but legally speaking, we elect a person not a party. They’re free to vote how the like.

Here in MN, Jesse Ventura was elected as a Reform party member and within a year had split with that party and officially became a member of the Independence party.