perhaps senior staffers should not be allowed to donate to anyone.
Respectfully disagree. Anyone should be permitted to donate any amount to anyone; that's called FREEDOM. But the recipient can't sell influence for money if he does not know who the donor is. So require that all political donations be anonymous. Make it a felony to reveal or to attempt to discover the identity of the donor.
So you get to back whoever you believe will act in your best interest, but you can't "buy" their favors. Combine that with term limits and you'll be rid of the career politicians, the "what's in it for me" class. Those remaining will be true public servants, who will go back to business after a couple of terms of service.
There will be a few who are worthy of continuing, and wish to do so; they can seek another elected position if they choose. But have them deal with retirement the way most of us have to do; no cushy pension funds.