Eric Trump proudly posted a photo of his vote for his father, Donald Trump, on social media.

There is only one problem – it is illegal in the state of New York to share a picture of an official election ballot.

"It is an incredible honour to vote for my father!" Mr Trump wrote in the now-deleted tweet. "He will do such a great job for the USA!"

There is a legal gray area in most states, but a sweeping Associate Press report found that it is definitely illegal in at least 18 US states to publicly share a photo of a ballot.

In New York, it is illegal to not only share a photo of a complete ballot, but also to indicate how a person cast their vote.

Is this the most bizarre campaign of all-time?