The GOP has been claiming Obama is a Kenyan Muslim for -8 years (including Trump's harrassment re: his birth certificate), and a recent poll [1] showed that 41% of republicans still believe he wasn't born in the US. So, it would appear that the US population has quite an appetite for these stories.
[1] http://www.mediaite.com/online/new-poll-shows-that-41-of-rep...