There’s a difference between a disagreement and something “abhorrent”. If it is not hyperbole, it could mean being a Jewish student with a senator who supported the “Jews will not replace us” Charlottesville march or dines with Nick Fuentes, or a closeted LGBTQ student whose senator furthers laws restricting their right to exist.
It’s not open-minded to accept s.o whose views&actions put you (or loved ones) in danger and it will not lead to growth but to degradation, being surrounded by ideas that make you want to scream. Btw I assume you know that, as a HS student and intern, you won’t be able to voice your opinions, let alone change anything.
A 2nd issue is that if @evenflow puts that experience on their resume, it is likely to be seen as a negative since the (state? US?) senator is well-known and extreme - either you’ll be assumed to want to further the same views (which will be a problem if later on you want to join a campaign better suited to your own views) or might even be seen as amoral (you’re ready to do sth like that to further your own goals at the expense of what you believe in, at an age most young people who want to join are idealistic - as you yourself recognize in your OP, that’s not a good look).
I would suggest you look for a local or state campaign -first, you’re more likely to make an impact because they have fewer staffer (v. Bringing coffees and photocopies around at a large campaign); second, there has to be one that aligns better with what you believe. School board races are especially relevant for HS students but anything at the town/township/district level is likely to welcome you.