what even is the point of this billboard? it would only serve to further entrench trumpists within their foxholes of delusion and wouldn't do anything to sway those who won't vote for him anyway.
it's not like the US has a horde of fence-sitters who haven't yet decided where to cast their ballot.
In any constituency there are undecided voters who don't know who they'll vote for until election day. Since the US is a two party system I suppose they are a huge factor in the end result even though there might not be too many of them.