[JeremyNT]

> So for this to be a reasonable opinion, it merely has to be reasonably possible for the claim to be true.

This position makes no sense to me, because the original statement indicates certainty. Therefore, you need to test the opposite of what you suggest, i.e. the statement can only be true if the election must contain substantial fraud.

When you negate the double negative, the claim in the tweet is:

> mail-in ballots will certainly be substantially fraudulent

Therefore if there is any chance that they will not contain substantial fraud, it is clearly a false statement.