Whoa. You cannot just say “it is OK to make serious allegations as long as they cannot be proven to be false.” No. It is an offense against the truth to make serious allegations that will harm someone’s reputation, let alone to talk about them as if they had been proven, unless the evidence that the allegations ARE true is very good. It is OK to say “this doesn’t look good” or “this association makes it reasonable to wonder if there is a connection” and so on. We don’t have to go to the “beyond a reasonable doubt” standard instead of the “preponderance of evidence” standard, either, provided we keep the standard we used in mind. We cannot make the jump to “they look guilty, so they must be guilty.” That is a jump to rash judgement.
When dealing with someone else’s reputation, the rule is “first, do no harm.” If it is not known to be true and it is not necessary to say it, don’t say it. Yes, when you are talking about someone in public office, someone you have to choose to support or not or to trust or not, you have a legitimate reason to discuss whether they are trustworthy and believable. They signed up for that; that is OK. No one in public office is entitled to your trust, that has to be earned with you, but the discussion still has to be kept fair. We do not have carte blanche to throw all consideration about respecting the demands of truth out the window just because we’re talking about politics and politicians. That’s hard, I fail in that myself sometimes, but that really is the standard we ought to have.
There is, by the way, no reason in the world to drag anyone else’s reputation in when discussing what current office holders are doing, except perhaps to argue that some certain deadline or amount of accomplishment is not realistic. Proving someone else is guilty of misconduct is not evidence that the conduct of the parties actually under discussion is OK.
If our candidate tells a lie, it is a lie. It is a falsehood. Trying to pass off falsehoods as the truth doesn’t become OK because of the misdirection that “his or her opponent lies, too.” No, that just means that they’re both guilty, not that they’re both placed in an alternative moral universe that is beyond accusation!
The time to bring charges of offenses against the truth against other candidates is when they say something false. It should not be dragged in as clothing to cover up an opponent’s lying.