I don’t think the dems believed that, The only reason they went to all the trouble to claim Obie was born in Hawaii is because they knew that he needed that to be eligible.
Otherwise they wouldn’t have bothered.
Hence all the MSM articles with the breathless "[BO], who was born in Hawai'i" as their lede. And at least one law professor who got all emotional over BO's birthplace. Something smells.
The reason for the forged birth certificate is that without it, there isn’t a shred of evidence that Barry is a citizen AT ALL.
There are only two possibilities:
The crudely-forged birth certificate is truthful in stating that Barry was born in Hawaii, in which case he is an ANCHOR BABY.
Barry was not born on U.S. soil, and is therefore an ILLEGAL ALIEN.