candidates have to get on the ballot in a seperate process for every state. It was actually a big thing this year as a snafu with biden on the ohio ballot https://www.nbc4i.com/news/local-news/columbus/why-joe-biden-could-be-excluded-from-ohios-ballot-and-what-is-to-come/. And not voting for the lesser of the two evils can let the greater evil win. bush and trump both lost the popular vote but got in and bush famously got in due to a court decision about hanging chads in florida. https://www.npr.org/2018/11/12/666812854/the-florida-recount-of-2000-a-nightmare-that-goes-on-haunting . So yes a few american not votes gave us the iraq war.