Trump was the only one who brought it up.
And I think it will be exposed.
Furthermore, it is unstated for the most part, but the dumb deep state is also under the opinion that at some point Trump will search and may find evidence that Obama is a foreigner born elsewhere. They have their rearguard action going and to turn it into an advance to end Trump’s presidency, and defending Obama’s past is part of it.
And it’s another reason why we have Mueller who is running around all over creation looking for some false pretext to use it against Trump.