What are the karmic consequences for someone supporting a Biden victory, if it can be proven beyond a shadow of a doubt that it was won by cheating, but if it is against an opponent who is an existential threat to the country?

The question presupposes that Biden is a more favorable and less dangerous president than Donald Trump. That is a highly subjective characterization that cannot be answered easily. The incumbent has a four-year track record, his opponent has a long history in politics but would be starting fresh as president. What would take place then under his leadership is yet to be determined. Given that all presidents are manipulated to some extent, and in many cases to a large extent, we would not presume to even characterize one president as being superior to another in advance. The question is: "To what degree would they be manipulated to override their positive inclinations, their moral precepts, and their humanitarian inclinations?" This usually happens often in service to state security and national defense as arguments for clandestine operations of all kinds that risk war as well as wars themselves that are billed as a preventive police action, but that, in fact, is what gets wars going—once shooting starts, things can easily escalate further. So this is simply reflecting how the Extraterrestrial Alliance can turn the good into bad in terms of the inherent character of someone in elective office. As a general rule of thumb, most of the time the government is not the friend of the people. It will be leading them astray and causing much harm at home or abroad or both—that is seen to by the Extraterrestrial Alliance.