From a historical perspective we know it is a fact that there’s been multiple instances of electoral fraud that have likely changed the results of the election. Examples are the fraud Democrats LBJ/JFK committed in the 1960 election that Nixon rightfully won. The Chicago Daley Democrat machine was notorious for committing electoral fraud for decades. So was the Tammany Hall Democrat machine in New York notorious for their electoral fraud.
These are just some examples of known cases of fraud by Democrats. For every known cases there’s likely a dozen more unknown cases where they weren’t busted.
And there was electoral fraud by Democrats in New Jersey local elections just two years ago. As well as many more cases.